Even a task as simple as this can be complicated without jQuery at our disposal. In plain JavaScript, we could add the highlightedclass as shown in the following code snippet:
復制代碼 代碼如下:
window.onload = function() {
var divs = document.getElementsByTagName('div');
for (var i = 0; i < divs.length; i++) {
if (hasClass(divs[i], 'poem-stanza') && !hasClass(divs[i], 'highlight')) {
divs[i].className += ' highlight';
}
}
function hasClass( elem, cls ) {
var reClass = new RegExp(' ' + cls + ' ');
return reClass.test(' ' + elem.className + ' ');
}
};
在我們自己處理的時候，甚至是這麼簡單的任務在不使用jquery的時候都會變得復雜。用原始的js，我們可以使用下面的代碼片段添加highlighted類：
Despite its length, this solution does not handle many of the situations that jQuery takes care of for us in Listing 1.2, such as the following:
• Properly respecting other window.onloadevent handlers
• Acting as soon as the DOM is ready
• Optimizing element retrieval and other tasks with modern DOM methods
盡管很長，但是這個解決方案依然沒有處理很多jquery在列表1.2中為我們做到的一些事情，比如下面的這些：
1、合適的處理其他的window.load事件
2、在DOM結構准備好的時候開始行動。
3、使用現代的DOM方法優化元素查找和其他任務。
We can see that our jQuery-driven code is easier to write, simpler to read, and faster to execute than its plain JavaScript equivalent.
我們可以清晰的看到我們的使用query的代碼比原生js代碼寫起來更容易，讀起來更簡單，運行起來更快。