javaScript and jQuery implement automatic loading-JS Tutorial-php.cn

javaScript and jQuery implement automatic loading

小云云

Release： 2017-12-07 16:01:29

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In this article, we will introduce to you the simplest code writing method to implement automatic loading using javaScript and jQuery. Hope it helps everyone.

1. JavaScript automatic loading

①Use onload in text: Execute onload after all content (including images) in the page has been loaded, as follows:

<body onload="alert(1)"></body>          <!-- 当有一个onload -->
<body onload="alert(2);alert(3);alert(4)"></body> <!-- 当有多个onload用分号隔开,依次弹出 2 3 4 -->

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②Use window.onload in the script: Execute window.onload after all the content in the page (including pictures) has been loaded, as follows:

window.onload = function(){...}; //正确写法，这是匿名函数

//------------↓多个window.onload的错误写法-------------
window.onload = function(){alert("text1");}; //不执行
window.onload = function(){alert("text2");}; //执行
//------------↑---------------------------------------

//------------↓多个window.onload的正确写法---------------------------
window.attachEvent("onload",function(){alert(&#39;a&#39;)});
window.attachEvent("onload",function(){alert(&#39;b&#39;)});
window.attachEvent("onload",function(){alert(&#39;c&#39;)});
//重点提示：在IE浏览器下用 (window.attachEvent)，会弹出 c b a 
//重点提示：其他浏览器下用 (window.addEventListener)，会弹出 a b c
//------------↑-----------------------------------------------------

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2. jQuery automatic loading

①After the DOM structure (excluding images) in the page is loaded Execute again (maybe the things associated with the DOM element have not been loaded), there are three ways to write, as follows:

$(document).ready(function(){...});//写法1，全称 
$(function(){...});        //写法2，简写 
jQuery(function($){...});     //写法3，简写

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② All in the page It is executed only after the elements (including images) are loaded, as follows.

$(window).load(function() {...}); //等于JavaScript的写法，如window.onload = function(){...};

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③Execute the anonymous function immediately. When an anonymous function is enclosed in brackets and then followed by parentheses, the anonymous function can be run immediately. There are two ways to write it, as follows:

(function( ){...})(); //Writing method 1, without adding parameters
(function($){...})(jQuery); //Writing method 2, adding parameters to avoid conflicts with other variables .

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