HTML5 creates a new timer requestAnimationFrame actual progress bar-H5 Tutorial-php.cn

Home

Web Front-end

H5 Tutorial

HTML5 creates a new timer requestAnimationFrame actual progress bar

一个新手

May 15, 2018 pm 05:26 PM

html5timer

Before requestAnimationFrame appeared, we generally used setTimeout and setInterval. So why did html5 add a new requestAnimationFrame? What problem did it appear to solve?

Advantages and features:

1) requestAnimationFrame will concentrate all DOM operations in each frame and complete them in one redraw or reflow, and redraw or reflow The time interval closely follows the browser's refresh frequency

2) In hidden or invisible elements, requestAnimationFrame will not be redrawn or reflowed, which of course means less CPU, GPU and Memory usage

3) requestAnimationFrame is an API provided by the browser specifically for animation. The browser will automatically optimize the method call during runtime, and if the page is not active, the animation will automatically pause, effectively Saves CPU overhead

In one sentence: this thing has high performance, will not freeze the screen, and automatically adjusts the frame rate according to different browsers. If you don’t understand it or don’t understand it, it doesn’t matter. This thing is related to the browser rendering principle. Let’s learn to use it first!

How to use requestAnimationFrame?

The usage method is similar to the timer setTimeout. The difference is that it does not need to set the time interval parameter.

var timer = requestAnimationFrame( function(){
             console.log( &#39;定时器代码&#39; );
                      } );

The parameter is a callback function and the return value is an integer. Indicates the number of the timer.

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script>
        window.onload = function(){
            var aInput = document.querySelectorAll( "input" ),
                timer = null;
            aInput[0].onclick = function(){
                timer = requestAnimationFrame( function say(){
                    console.log( 1 );
                    timer = requestAnimationFrame( say );
                } );
            };
            aInput[1].onclick = function(){
                cancelAnimationFrame( timer );
            }
        }
    </script>
</head>
<body>
    <input type="button" value="开启">
    <input type="button" value="关闭">
</body>
</html>

cancelAnimationFrame is used to close the timer

This method needs to handle compatibility:

Simple compatibility:

window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       ||
          window.webkitRequestAnimationFrame ||
          window.mozRequestAnimationFrame    ||
          function( callback ){
            window.setTimeout(callback, 1000 / 60);
          };
})();

If you browse If the browser does not recognize AnimationFrame, use setTimeout for compatibility.

Use three different timers (setTimeout, setInterval, requestAnimationFrame) to implement the loading of a progress bar

1. setInterval method:

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        p{
            width:0px;
            height:40px;
            border-radius:20px;
            background:#09f;
            text-align:center;
            font:bold 30px/40px &#39;微软雅黑&#39;;
            color:white;
        }
    </style>
    <script>
        window.onload = function(){
            var oBtn = document.querySelector( "input" ),
                oBox = document.querySelector( "p" ),
                timer = null, curWidth = 0,
                getStyle = function( obj, name, value ){
                    if( obj.currentStyle ) {
                        return obj.currentStyle[name];
                    }else {
                        return getComputedStyle( obj, false )[name];
                    }
                };
            oBtn.onclick = function(){
                clearInterval( timer );
                oBox.style.width = &#39;0&#39;;
                timer = setInterval( function(){
                    curWidth = parseInt( getStyle( oBox, &#39;width&#39; ) );
                    if ( curWidth < 1000 ) {
                        oBox.style.width = oBox.offsetWidth + 10 + &#39;px&#39;;
                        oBox.innerHTML = parseInt( getStyle( oBox, &#39;width&#39; ) ) / 10 + &#39;%&#39;;
                    }else {
                        clearInterval( timer );
                    }
                }, 1000 / 60 );
            }
        }
    </script>
</head>
<body>
    <p>0%</p>
    <p><input type="button" value="ready!Go"></p>
</body>
</html>

#2. setTimeout method

<script>
        window.onload = function(){
            var oBtn = document.querySelector( "input" ),
                oBox = document.querySelector( "p" ),
                timer = null, curWidth = 0,
                getStyle = function( obj, name, value ){
                    if( obj.currentStyle ) {
                        return obj.currentStyle[name];
                    }else {
                        return getComputedStyle( obj, false )[name];
                    }
                };
            oBtn.onclick = function(){
                clearTimeout( timer );
                oBox.style.width = &#39;0&#39;;
                timer = setTimeout( function go(){
                    curWidth = parseInt( getStyle( oBox, &#39;width&#39; ) );
                    if ( curWidth < 1000 ) {
                        oBox.style.width = oBox.offsetWidth + 10 + &#39;px&#39;;
                        oBox.innerHTML = parseInt( getStyle( oBox, &#39;width&#39; ) ) / 10 + &#39;%&#39;;
                        timer = setTimeout( go, 1000 / 60 );
                    }else {
                        clearInterval( timer );
                    }
                }, 1000 / 60 );
            }
        }
    </script>

3. requestAnimationFrame method

<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        p{
            width:0px;
            height:40px;
            border-radius:20px;
            background:#09f;
            text-align:center;
            font:bold 30px/40px &#39;微软雅黑&#39;;
            color:white;
        }
    </style>
    <script>
        window.onload = function(){
            var oBtn = document.querySelector( "input" ),
                oBox = document.querySelector( "p" ),
                timer = null, curWidth = 0,
                getStyle = function( obj, name, value ){
                    if( obj.currentStyle ) {
                        return obj.currentStyle[name];
                    }else {
                        return getComputedStyle( obj, false )[name];
                    }
                };
            oBtn.onclick = function(){
                cancelAnimationFrame( timer );
                oBox.style.width = &#39;0&#39;;
                timer = requestAnimationFrame( function go(){
                    curWidth = parseInt( getStyle( oBox, &#39;width&#39; ) );
                    if ( curWidth < 1000 ) {
                        oBox.style.width = oBox.offsetWidth + 10 + &#39;px&#39;;
                        oBox.innerHTML = parseInt( getStyle( oBox, &#39;width&#39; ) ) / 10 + &#39;%&#39;;
                        timer = requestAnimationFrame( go );
                    }else {
                        cancelAnimationFrame( timer );
                    }
                } );
            }
        }
    </script>
</head>
<body>
    <p>0%</p>
    <p><input type="button" value="ready!Go"></p>
</body>
</html>

The above is the detailed content of HTML5 creates a new timer requestAnimationFrame actual progress bar. For more information, please follow other related articles on the PHP Chinese website!

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Is H5 a Shorthand for HTML5? Exploring the DetailsApr 14, 2025 am 12:05 AM

H5 is not just the abbreviation of HTML5, it represents a wider modern web development technology ecosystem: 1. H5 includes HTML5, CSS3, JavaScript and related APIs and technologies; 2. It provides a richer, interactive and smooth user experience, and can run seamlessly on multiple devices; 3. Using the H5 technology stack, you can create responsive web pages and complex interactive functions.

H5 and HTML5: Commonly Used Terms in Web DevelopmentApr 13, 2025 am 12:01 AM

H5 and HTML5 refer to the same thing, namely HTML5. HTML5 is the fifth version of HTML, bringing new features such as semantic tags, multimedia support, canvas and graphics, offline storage and local storage, improving the expressiveness and interactivity of web pages.

What Does H5 Refer To? Exploring the ContextApr 12, 2025 am 12:03 AM

H5referstoHTML5,apivotaltechnologyinwebdevelopment.1)HTML5introducesnewelementsandAPIsforrich,dynamicwebapplications.2)Itsupportsmultimediawithoutplugins,enhancinguserexperienceacrossdevices.3)SemanticelementsimprovecontentstructureandSEO.4)H5'srespo

H5: Tools, Frameworks, and Best PracticesApr 11, 2025 am 12:11 AM

The tools and frameworks that need to be mastered in H5 development include Vue.js, React and Webpack. 1.Vue.js is suitable for building user interfaces and supports component development. 2.React optimizes page rendering through virtual DOM, suitable for complex applications. 3.Webpack is used for module packaging and optimize resource loading.

The Legacy of HTML5: Understanding H5 in the PresentApr 10, 2025 am 09:28 AM

HTML5hassignificantlytransformedwebdevelopmentbyintroducingsemanticelements,enhancingmultimediasupport,andimprovingperformance.1)ItmadewebsitesmoreaccessibleandSEO-friendlywithsemanticelementslike,,and.2)HTML5introducednativeandtags,eliminatingthenee

H5 Code: Accessibility and Semantic HTMLApr 09, 2025 am 12:05 AM

H5 improves web page accessibility and SEO effects through semantic elements and ARIA attributes. 1. Use, etc. to organize the content structure and improve SEO. 2. ARIA attributes such as aria-label enhance accessibility, and assistive technology users can use web pages smoothly.

Is h5 same as HTML5?Apr 08, 2025 am 12:16 AM

"h5" and "HTML5" are the same in most cases, but they may have different meanings in certain specific scenarios. 1. "HTML5" is a W3C-defined standard that contains new tags and APIs. 2. "h5" is usually the abbreviation of HTML5, but in mobile development, it may refer to a framework based on HTML5. Understanding these differences helps to use these terms accurately in your project.

What is the function of H5?Apr 07, 2025 am 12:10 AM

H5, or HTML5, is the fifth version of HTML. It provides developers with a stronger tool set, making it easier to create complex web applications. The core functions of H5 include: 1) elements that allow drawing graphics and animations on web pages; 2) semantic tags such as, etc. to make the web page structure clear and conducive to SEO optimization; 3) new APIs such as GeolocationAPI support location-based services; 4) Cross-browser compatibility needs to be ensured through compatibility testing and Polyfill library.

See all articles