js animation timer usage tutorial

This time I will bring you a tutorial on how to use the js animation timer. What are theprecautionswhen using the js animation timer? The following is a practical case, let’s take a look.

Broadly speaking: All visual presentations changed through js are called animations; for example, buttons, links and other elementsInteractive feedback.

In a narrow sense: the visual animation effect produced by continuously calling js functions through timers to change element attributes.

Timer

Timer is the core technology of JavaScript animation;

setTimeout(), setInterval() are well known and often used in the past;

Usually they do something auxiliary and icing on the cake;

Careful people may find a phenomenon, switching from other tabs to the page with loop animation will cause lag and rapid frame switching;

The problem lies in their internal operating mechanism;

Understand setTimeout

It is recommended to use the function form for the first parameter, the string form will be parsed twice, and eval is the same Question;

More than two parameters, there can be more, see example 1;

This points to the problem, see example 2;

The return value is an integer;

clearTimeout(timer) cancels the timer;

setInterval, clearInterval are the same as above;

Example 1:

setTimeout(function(a,b){ console.log(a+b); },1000,1,1)；

Example 2:

var a = 0; function foo(){ console.log(this.a); }; var obj = { a : 2, foo:foo } setTimeout(obj.foo,100);

Running mechanism

Example:

setTimeout(function(){ console.log(1); }); console.log(0);

Reason: Join the queue and block execution.

setTimeout legend:

setInterval legend:

callback function, usually triggered before the browser's default action, see example 4;

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

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