requestAnimationFrame() functions, which can be used to call a specific function over a set period of time. El método setTimeout() establece un temporizador que ejecuta una función o una porción de código después de que transcurre un tiempo establecido. mouseout 事件在定点设备（通常是鼠标）移动至元素或其子元素之外时，会在该元素上触发。var image = new Image (); img. Polyfill. ; We set throttlePause to true for the next iteration. all () The Promise. To find out if the mouse has not moved (hovered) simply use setTimeout to call. See the following example: To take advantage of the readability improvement and language features offered by promises, the Promise () constructor allows one to transform the callback-based API to a promise-based one. Uint8Array. 8 hours agoWindow: beforeunload event. For additional examples that use requestAnimationFrame (), see the Document: scroll event page. "); }, "1000"); Pero en muchos casos, la coerción de tipo implícito puede conducir a resultados inesperados y sorprendentes. 由 setTimeout () 执行的代码是从一个独立于调用 setTimeout 的函数的执行环境中调用的。. function logThis() { "use strict"; console. Internet Explorer 9 and below), you can include this polyfill which enables the HTML5 standard parameter-passing. Note, however, that input events and. This value can be passed to clearTimeout() to cancel the timeout. The URL. Access to and manipulation of. Determines whether scrolling is instant or animates smoothly. If you need repeated executions, use setInterval () instead. setTimeout ( [delay [, value [, options]]]) timersPromises. (if executed again during this interval):Here’s a breakdown of what’s happening: throttlePause is initially undefined, so the function moves on to the next line. Window: load event. This value can be passed to clearTimeout() to cancel the timeout. Await causes the code to wait until the promise object is fulfilled,. css() Timers¶ There are two timer functions that allow us to execute code at a later time. are the string arguments that will be passed on to the functions as their arguments to be executed completely. This is because: Function. As we learned at the start of the article, the return value of setTimeout is a numerical ID which can be used to cancel the timer in conjunction with the clearTimeout function. Timeout", and it is possible to use it as follows:Date. 值得注意的是，setInterval() 和 setTimeout() 共享同一个 ID 池，并且 clearInterval() 和 clearTimeout() 在技术上是可互换使用的。 但是，我们应该匹配使用 clearInterval() 和. JavaScript. window; //. bind할 인수(argument)가 제공되지 않으면 실행 스코프 내의 this는 새로운. setInterval () O método setInterval () oferecido das interfaces Window e Worker, repetem chamadas de funções ou executam trechos de código, com um tempo de espera fixo entre cada chamada. open(). There are two native functions in the JavaScript library used to accomplish these tasks: setTimeout () and setInterval (). window. The setInterval () method, offered on the Window and WorkerGlobalScope interfaces, repeatedly calls a function or executes a code snippet, with a fixed time delay between each call. Learn More. 引擎的一般算法：. an hour ago; Bump markdownlint-cli2 from 0. If you need to pass one or more arguments to your callback function, but need it to work in browsers which don't support sending additional parameters using either setTimeout() or setInterval() (e. The third parameter onwards will be the parameters that the callback function would. setTimeout is a method of the global window object. 8 hours agoWhen calling setTimeout or setInterval, a timer thread in the browser starts counting down and when time up puts the callback function in javascript thread's execution stack. exports. You can read more details in the MDN documentation. 2 hours ago; update File-System-Access mdn/content. Using Promise. all () may be more appropriate if the tasks are dependent on each other, or if you'd like to. 6. addEventListener() from the target. When the fetch request is initiated, we pass in the AbortSignal as an option inside the request's options. function debounce( callback, delay ) { let timeout; return function() { clearTimeout( timeout ); timeout = setTimeout( callback, delay. setTimeout() is a function serviced globally by the window object provided by the user’s browser. an hour ago; Bump markdownlint-cli2 from 0. If you need to pass one or more arguments to your callback function, but need it to work in browsers which don't support sending additional parameters using either setTimeout() or setInterval() (e. The Element. An arrow function expression is a compact alternative to a traditional function expression, with some semantic differences and deliberate limitations in usage: Arrow functions don't have their own bindings to this, arguments, or super, and should not be used as methods. The commonly used syntax of JavaScript setTimeout is: setTimeout (function, milliseconds); Its parameters are: function - a function containing a block of code. Thus, the following expressions all return the same window object: window. The window property of a Window object points to the window object itself. prototype. Vea el siguiente ejemplo:Description. However, content scripts get a "clean" view of the DOM. Note: This feature is available in Web Workers. We're passing in two parameters: the string "click", to indicate that we want to listen to the click event. window. A percentage value refers to the width of the reference. Learn to style content. The window. For compatibility, you can include bind's source, which is available at MDN, allowing you to use it in browsers that don't support it natively. Code: Whenever you may need to stop a setTimeout, store its value in a variable: const timeoutID = setTimeout (f, 1000); // Some code clearTimeout (timeoutID); (Think of this number as the ID of a setTimeout. bind를 사용하여 setTimeout 내에 콜백 함수를 만들 때, thisArg로 전달된 원시 값은 객체로 변환됩니다. MDN Web Docs WindowOrWorkerGlobalScope. 当你向 setTimeout () 传递一个函数时，该函数中的 this 指向跟你的期望可能不同，这个问题在 JavaScript 参考 中进行了详细解释。. 执行到一个由 setTimeout() 或 setInterval() 创建的 timeout 或 interval. There are a number of reasons why a timeout may take longer to fire than anticipated. Learn how to use the setInterval () method to repeatedly call a function or execute a code snippet with a fixed time delay between each call. The Element. A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment ). If the promise is rejected, the. Polyfill. To execute the function only once, use the setTimeout() method instead. instant: scrolling should happen instantly in a single jump. 8. That's why you can call setTimeout (). If it's still confusing, take a look at the MDN docs for Promise. Si la valeur de l'expression n'est pas une promesse, elle est convertie en une promesse résolue ayant cette. Downvoted. Use timerID = setTimeout(startClock, 1000); instead. setTimeout is a built-in Node. behavior. Browsers not supporting strict mode will run strict mode code with different behavior from browsers that do, so don't rely on. disconnect() Stops the MutationObserver instance from receiving further notifications until and unless observe() is called again. The specifics of how it works varies from browser to browser, but there is a de facto set of features that are typically provided. もし setTimeout() が呼び出されたときの delay 値が数値でなかった場合、暗黙のうちに型強制が行われ、その値を数値に変換します。例えば、以下のコードは delay の値とし. window. process. 禁止使用settimeout. Element is the most general base class from which all element objects (i. Providing setTimeout a negative time will not always result in the callback function being called. Use encodeURI (), encodeURIComponent (), decodeURI (), or decodeURIComponent () to encode and decode escape sequences for special characters. Using the Popover API. It works with setTimeout because of two conditions in the browser:. The frequency of calls to the callback function will generally match the display. Run them separately. If a function expression is named, the name property of the function is set. 2. About; Blog; Careers; Advertise with us; Support. We would like to show you a description here but the site won’t allow us. forEach(logThis); // undefined, undefined, undefined. 試したら非 strict モードでも strict モード 2 でも setTimeout コールバックの既定の this の値は、 window オブジェクトだった。 setTimeout(callback) は内部で callback. await is usually used to unwrap promises by passing a Promise as the expression. Jul 30, 2012 at 4:00. setInterval () global function. The event continues to propagate as usual, unless one of its event listeners calls stopPropagation () or. setTimeout). This HTML reference describes all elements and attributes of HTML, including global attributes that apply to all elements. prototype. setTime () The setTime () method of Date instances changes the timestamp for this date, which is the number of milliseconds since the epoch, defined as the midnight at the beginning of January 1, 1970, UTC. from the summary of each of your provided links (hint hint - see words in bold) : setInterval - "Calls a function or executes a code snippet repeatedly, with a fixed time delay between each call to that function. src="imageURL"; image. Alternatively, you can use setTimeout(postinsql. You can also consult the setTimeout() MDN docs. Apr 30, 2021 at 23:03. See the following example:If you're new to setTimeout() MDN has a pretty straightforward guide you can play around with. 193k 38 38 gold badges 301 301 silver badges 306 306 bronze badges. setTimeout(fn, 0) We can take the above-described behavior to our advantage if we want to execute some tasks without blocking the main thread for too long. The worker thread can perform tasks without interfering with the user interface. The default value is Infinity, meaning that getCurrentPosition () won't return until the position is available. The dispatchEvent () method of the EventTarget sends an Event to the object, (synchronously) invoking the affected event listeners in the appropriate order. So in your second example, you call test1 first, and it schedules a call to the anonymous callback for a second later, then returns. Check out the MDN description on the concurrency model and the event loop, and it should become clear what's going on (that MDN resource is a real gem). reload () differs from the origin of the page that owns the Location object. It will evaluate the source string as a script body, which means both statements and expressions are allowed. 既定では、 setTimeout() 内部の this キーワードは globalThis、すなわちブラウザーでは window に設定されます。 暮らすメソッドを使用して this がクラスインスタンスを参照するようにする必要がある場合、インスタンスを保守するために、明示的に this をコール. 11. signal property. Time in milliseconds to wait for the document to finish loading. Possible values are: The page content may be at least partially visible. showUp() This function simply calls the showAndHide function with a specific delay and hole. At the time the promise is returned to the caller, the operation often isn't finished, but the promise object provides methods to handle the. g. Specifies the number of pixels along the X axis to scroll the window or element. If the variable is still the target value on the next interval, execute your function. __filename. In the version without the parentheses, the value passed to setTimeout as first argument is a reference to a function, which is impossible to resolve further/simplify. In the following code, we see a call to queueMicrotask () used to schedule a microtask to run. setTimeout is a built-in JavaScript function that allows you to execute a function or a block of code after a specified delay. When using setRequestHeader (), you must call it after calling open (), but before calling send () . In JavaScript, closures are created every time a function is created, at function creation time. clearTimeout". Array. From MDN "timeoutID is the numerical ID of the timeout, which can be used later with window. ScriptRuntime. The reason is that each setTimeout creates a new closure that closes over the i variable, but if the i is not scoped to the loop body, all closures will reference the same variable when they eventually get called — and due to the asynchronous nature of setTimeout, it will happen after the loop has already exited,. Recall that setTimeout() is explained in the JavaScript and the DOM: Events lesson. The HTML DOM API is made up of the interfaces that define the functionality of each of the elements in HTML, as well as any supporting types and interfaces they rely upon. setTimeout (functionRef, delay) // Parameters // functionRef - A **function** to be executed after the timer expires. 1. Improve this answer. If false, the bottom of the element will be aligned to the bottom of the visible area of the scrollable ancestor. 禁止使用settimeout. The nested setTimeout method is more flexible than setInterval. It allows users to execute callbacks after a period of time expressed in milliseconds. Promise 是一個表示非同步運算的最終完成或失敗的物件。 由於多數人使用預建立的 Promise，這個導覽會先講解回傳 Promise. Esse ID é o retorno da função setTimeout(). グローバルの setTimeout() メソッドは、時間切れになると関数または指定されたコードの断片を実行するタイマーを設定します。. Examples of what I'm referring to: isNaN isFinite requestAnimationFrame setTimeout setInterval. offmainthreadcomposition. 3: let n: ReturnType<typeof setTimeout>; n = setTimeout (cb, 500); It is nice and seems to be preferred over explicit casting. window. The state indicates that the DOMContentLoaded event is about to fire. The Page Visibility API adds the following properties to the Document interface: Returns true if the page is in a state considered to be hidden to the user, and false otherwise. The number is the id of the timer. After the beginning of the element (first child) afterend. An uppercase "A" is reported as 65 by all. To cancel the timeout, this key can be passed to the clearTimeout () function as a parameter. Element: clientWidth property. Given below is the syntax mentioned: 1. 2. This value can be passed to clearTimeout() to cancel the timeout. hoge ('すぐ実行されてしまう')の結果は undefined のため、. This name is then local only to the function body (scope). But does this mean it. bind(this, sp. OP wants to refresh an image, and 3 out of 4 solutions given here suggest to reload the whole page. You can also consult the setTimeout MDN docs. eval () is a function property of the global object. Follow answered Jun 5, 2012 at 22:21. to the initial asyncGenerator function. setTimePassed (); }, 400); 'setTimeout' is. The functional areas included in the HTML DOM API include: Access to and control of HTML elements via the DOM. I haven't tested this myself, but like Thomasz said, it's probably better to be safe. 호출 함수의 this 키워드 값을 설정하는 일반적인 규칙이 여기서도 적용되며, this 를 호출 시 지정하지도 않았고 bind 로 바인딩하지도 않은 경우 기본 값인 window. For. g. 事件循环. log("Hello World"); } setTimeout(greeting); setTimeout() method using named function as its argument Description. setTimeoutImpl(code, timeout, params); + } + + @Deprecated + public int setTimeout(final Object code, int timeout, final Object language) {+ return setTimeoutImpl(code, timeout, ScriptRuntime. Product help; Report an issue; Our communities. As a getter, it approximates the text the user would get if they highlighted the contents of the element with the cursor and then copied it to the clipboard. MDN Docs: setTimeout () From the docs: The global setTimeout () method sets a timer which executes a function or specified piece of code once the timer expires. Element: classList property. setTimeout() にメソッドを. Since node v15, you can use timers promise API. window. Buttons can fire lots of other events, such as "mouseover" when the user moves. The tag name of a custom element previously defined via customElements. setTimeout. ; setTimeout starts a timer to run the function. 이를. If you need to pass an argument to your callback function, but need it to work in Internet Explorer, which doesn't support sending additional parameters (neither with setTimeout() or setInterval()) you can include this IE-specific compatibility code which will enable the HTML5 standard parameters. More info on setTimeout (MDN). A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment ). Learn to structure web content with HTML. If the parameter provided does not identify a previously established action, this method does nothing. setTimeout is. In web pages, the window object is also a global object. 참고: 노트: 이 메소드는 ParentNode 믹스인의 querySelectorAll (). 1 second = 1000 milliseconds. See EventTarget. Further to what @nnnnnn said, if you are using ES6 you can use arrowed functions. From MDN setTimeout (): Code executed by setTimeout () is run in a separate execution context to the function from which it was called. This is in contrast to DOMContentLoaded, which is fired as soon as the page DOM has been loaded, without waiting for resources to finish loading. It requests the browser to call a user-supplied callback function prior to the next repaint. ; idle, prepare: only used internally. Alarms do not persist across browser sessions. Basically I am creating a sort of 8-bit city scene. Esencialmente, una promesa es un objeto devuelto al cual se adjuntan. Just google setTimeout MDN (and bookmark MDN) if this isn't clear to you. Then you call test2 which prints immediately. process. JavaScript. The default clause of a switch statement will be jumped to if no case matches the expression's value. The XMLHttpRequest. then メソッドは Promise を返すので、メソッド連鎖ができます。. then (). The removeEventListener() method of the EventTarget interface removes an event listener previously registered with EventTarget. The code below schedules a timeout to occur in zero milliseconds, then enqueues a microtask. In the following snippet, we aim to download a video using the Fetch API. A positive long value representing the maximum length of time (in milliseconds) the device is allowed to take in order to return a position. The hostname property of the Location interface is a string containing the domain of the URL. 10. だから何も起こらない。. jQuery (via library) $. A Promise is an object representing the eventual completion or failure of an asynchronous operation. index; } }) (); setTimeout. For more information about the onRejected handler, see the catch () reference. You can use any common looping statement, such as:window. The global object of the DOM has a method setTimeout (). 6 hours ago; fix: typos in JavaScript Guide, Expressions and operators mdn/content. Functions are generally called in first-in-first-out order;. , 4)), which would slow down execution even more. ) Share. Simple, Settimout function get triggered after 6000 milliseonds. Event: preventDefault () method. Because push () accepts a variable number of arguments, you can also push multiple elements at once. So it defines an addEventListener() function, which we are calling here. The returned timeoutID is a positive integer value which identifies the timer created by the call to setTimeout(). g. Promise. (以下、MDN)のコンテンツを翻訳した内容を基に構成されています。 構成について異なる点も含まれますので、下記の項目を確認し、必要に応じて元のコンテンツをご確認ください。The returned timeoutID is a positive integer value which identifies the timer created by the call to setTimeout(). For example, all iterative array methods and related ones like Set. However, if a custom image is desired, the DataTransfer. onload = function () { ctx. How does setInterval() differ from setTimeout() ? Unlike setTimeout() which executes a function just once after a delay, setInterval() will repeat a function every set number of seconds. setTimeout()은 비동기 함수로서, 함수 스택의 다른 함수 호출을 막지 않습니다. The Popover API provides developers with a standard, consistent, flexible mechanism for displaying popover content on top of other page content. now () To determine how much time has elapsed since a particular point in your code, you can do something like this: js. Once established, you can reference elements in the array using the object's methods, or using standard array index syntax (that is, using bracket notation). setTimeout(hoge('すぐ実行されてしまう'),4000) では、hogeがまず評価 (実行)され、setTimeoutはその結果をwait後に実行する。. 달리 말하자면, setTimeout()을 사용해서 다음 함수 호출을 "일시정지" 할 수는 없습니다. Since node v15, you can use timers promise API. See also clearTimeout() example. alarm created in background script will fire onAlarm event in background script, options. setImmediateAnother approach – the variable parameter list. As specified in the HTML standard, browsers will enforce a minimum timeout of 4 milliseconds once a nested call to setTimeouthas been scheduled 5 times. g. Second, the call stack is empty. JavaScript standards. Historical factoid: In days of VBScript, in JScript, setTimeout's third parameter was the language, as a string, defaulting to "JScript" but with the option to use "VBScript". setTimeout. This is exactly where we see clamping. showUp() This function simply calls the showAndHide() function with a specific delay and hole. While the article Using the MediaStream Recording API demonstrates using the MediaRecorder interface to capture a MediaStream generated by a hardware device, as returned by navigator. 3: let n: ReturnType<typeof setTimeout>; n = setTimeout (cb, 500); It is nice and seems to be preferred over explicit casting. description: 'Positive integer value which identifies the timer created by the call to setTimeout this value can be passed to clearTimeout to cancel the timeout' export function setTimeout(idFn: Function, id: number|number): number;The Worker interface of the Web Workers API represents a background task that can be created via script, which can send messages back to its creator. It’s all nice and easy when the code is synchronous: const timeoutId = setTimeout (doSomeWorkLater, 1500); //. For expressions, it's the value the expression evaluates to. The scripts will then be interrupted and a script timeout. requestIdleCallback(processPendingAnalyticsEvents, { timeout: 2000 }); If your callback is executed because of the timeout firing you’ll notice two things:3、3、3 とログ出力します。 なぜかと言うと、それぞれの setTimeout が i 変数を閉じる新しいクロージャを作成しますが、i がループ本体のスコープでない場合、すべてのクロージャは最終的に呼び出されたときに同じ変数を参照します。 そして setTimeout の非同期であるため、すでにループが終了. showUp() This function simply calls the showAndHide() function with a specific delay and hole. 바인딩 함수를 new 연산자로 생성한 경우 무시됩니다. Usar promesas. The queueMicrotask () method, which is exposed on the Window or Worker interface, queues a microtask to be executed at a safe time prior to control returning to the browser's event loop. push () to append an element to an array. – gion_13. The DOM specifies that the global object has a property named window, which is a reference back to the global object. fill (null), xIsNext: true, }), 3000); } Secondly, since you are calculating winner in render function, you would add another state variable to keep track of the countdown and then trigger. Window: window property. setTimeout () (en-US). There's also a polyfill for it. This is because setTimeout callbacks are only executed after 2 conditions are met: First, the timer has expired in the web API. Assign an arrow function to handle Filtering the Seasons using the setTimeOut() method setTimeout()-MDN-DOCS Where 500 is the time the function is executed for that time andBelow is a summary of what a debounce function does, explained in a couple of lines with a demo. See also clearTimeout() example. They exist only in the scope of modules, see the module system documentation: __dirname. See also clearTimeout() example. Yes, you can have a setTimeout () inside another one -- this is the typical mechanism used for repeating timed events. setTimeout(makeTimeout. This example shows a method which opens a window and a second one which closes the window; this demonstrates how to use Window. Date. Syntax. Web Technologies;A simple example showing a fetch operation that will timeout if unsuccessful after 5 seconds, is shown below. If this method is called several times with the same header, the values are merged into one single request header. The getItem() method of the Storage interface, when passed a key name, will return that key's value, or null if the key does not exist, in the given Storage object. proxy or Function. bind(null, topicId), 4000);, however passing extra arguments is simpler, and that's preferable. With this API, you can send messages to a server and receive event-driven responses without having to poll the server for a reply. To clear all timeouts they must be "captured" first: Place the below code before any other script and it will create a wrapper function for the original setTimeout & clearTimeout. This enables developers to perform background and low priority work on the main event loop, without impacting latency-critical events such as animation and input response. It executes the given function (or evaluates the given string) after the time given as second parameter passed. The console object provides access to the browser's debugging console (e. Let's see a quick example using the above snippet (we'll discuss what's happening in it later): async function performBatchActions() { // perform an API call await performAPIRequest() // sleep for 5 seconds await sleep(5) // perform an API call again await performAPIRequest() } This function performBatchActions, when called, simply executes. For. setTimeout (en-US)を呼び出すと、2 番目の引数として渡された時間が経過した後、メッセージがキューに追加され. 指定された引数で前回確立されたアクションを識別できなかった場合、このメソッドは何も行いません。. Reasons for delays longer than specified. 각각의 메시지에는 메시지를 처리하기 위한 함수가 연결되어 있습니다. Recall that setTimeout() is explained in the JavaScript and the DOM: Events lesson. Promise. setTimeout (要执行的代码, 等待的毫秒数) setTimeout (JavaScript 函数, 等待的毫秒数) 在测试代码中我们可以看到页面在开启三秒后, 就会出现一个 alert 对话框。. aria-live: The aria-live=POLITENESS_SETTING is used to set the priority with which screen reader should treat updates to live regions - the possible settings are: off, polite or assertive. 3. The default clause of a switch statement will be jumped to if no case matches the expression's value. from the summary of each of your provided links (hint hint - see words in bold) : setInterval - "Calls a function or executes a code snippet repeatedly, with a fixed time delay between each call to that function. js. MDN Web Docs コミュニティーについてもっと知り、仲間になるにはこちらから。. This method returns an interval ID which uniquely identifies the interval, so you can remove it later by calling clearInterval (). async-animations. The setTimeout ( ) method defers the execution of the JavaScript statements in the string code for delay milliseconds. confirm () instructs the browser to display a dialog with an optional message, and to wait until the user either confirms or cancels the dialog. You can write the function directly when passing it, or you can also refer to a named function as shown below: function greeting(){ console. setTimeout() Executes the function specified by function in delay milliseconds. Two things. Recording a media element. 2. Microsoft Edge, Firefox 40, iOS Safari and desktop Safari 8. The keydown and keyup events provide a code indicating which key is pressed, while keypress indicates which character was entered. The bind () function creates a new bound function. load イベントは、ページ全体が、スタイルシートや画像などのすべての依存するリソースを含めて読み込まれたときに発生します。これは DOMContentLoaded が、ページの DOM の読み込みが完了すれば、リソースの読み込みが完了するのを待たずに発生するのと対照的. En otras palabras, no puede usar setTimeout () para crear una "pausa" antes de que se active la siguiente función en la pila de funciones. In the second loop, the variable i was declared using the let keyword: variables declared with the let (and const) keyword are block-scoped (a block is anything between { }). clientWidth property is zero for inline elements and elements with no CSS; otherwise, it's the inner width of an element in pixels. 0 coins. 事件循环 的概念非常简单。. setTimeout(undefined,4000) を実行している事になる。. Follow answered Aug 1, 2017 at 14:48. Second, the call stack is empty. Canceling a Timer. 2. The Promise chain would " swallow " this exception (it wouldn't get thrown globally), so to get out of this Promise chain, we have to call setTimeout from. 다음. bind(this, sp. sandboxed modals flag. Note: Be aware that clearRect () may cause unintended side effects if you're not using paths properly. Games are constantly looping through these stages, over and over, until some end condition occurs (such as. The feature can be emulated in a few different ways: postMessage can be used to trigger an immediate but yielding callback. The switch statement evaluates an expression, matching the expression's value against a series of case clauses, and executes statements after the first case clause with a matching value, until a break statement is encountered. Roko C. setTimeout () is capable of receiving multiple parameters where the first is a callback function. So if there are other time-consuming functions being executed when time up. They can also see any changes that were made to the DOM by page scripts. ) Here, argument 1, argument 2. Share. More specific classes inherit from Element. After enabling OMTA, try running the above test again. Scroll event throttling. XMLHttpRequest: timeout property. 13. requestIdleCallback() method queues a function to be called during a browser's idle periods. The clearImmediate method can be used to clear the immediate actions, just like clearTimeout for setTimeout (). Only the function parameter you have passed will be called by setTimeout () when the timeout occurs. getElementById读取信息，但是使用document. All values that are not undefined or objects with a.