javaScript Patterns 2.3 For loops 2014-05-17 10:14 by 小郝（Kaibo Hao）, ... 阅读, ... 评论, 收藏, 编辑 HTMLCollections are objects returned by DOM methods such as:
• document.getElementsByName()
• document.getElementsByClassName()
• document.getElementsByTagName()
HTMLCollections, which were introduced before the DOM standard and are still in use today
document.images
All IMG elements on the page
document.links
All A elements
document.forms
All forms
document.forms[0].elements
All fields in the first form on the page
// used i+=1 instead of i++ to follow the rule of JSLint
for (var i = 0, max = myarray.length; i < max; i += 1) { // do something with myarray[i]}
• Use one less variable (no max)
• Count down to 0, which is usually faster because it's more efficient to compare to 0 than to the length of the array or to anything other than 0
The first modified pattern is:
var i, myarray = [];for (i = myarray.length; i--;) { // do something with myarray[i]}
And the second uses a whileloop:
var myarray = [],i = myarray.length;while (i--) { // do something with myarray[i]}