The name of the DOM function is actually getElementsByClassName , not getElementByClassName , simply because more than one element on the page can have the same class, hence: Elements .(DOM函数的名称实际上是getElementsByClassName ，而不是getElementByClassName ，仅仅是因为页面上的多个元素可以具有相同的类，因此： Elements 。)
The return value of this will be a NodeList instance, or a superset of the NodeList (FF, for instance returns an instance of HTMLCollection ).(这一返回值将是一个节点列表实例，或所述的一个超集NodeList （FF，例如返回的一个实例HTMLCollection ）。) At any rate: the return value is an array-like object:(无论如何：返回值是一个类似数组的对象：)
var y = document.getElementsByClassName('foo');
var aNode = y[0];
If, for some reason you need the return object as an array, you can do that easily, because of its magic length property:(如果由于某种原因需要返回对象作为数组，则由于其不可思议的length属性，可以轻松地做到这一点：)
var arrFromList = Array.prototype.slice.call(y);
//or as per AntonB's comment:
var arrFromList = [].slice.call(y);
As yckart suggested querySelector('.foo') and querySelectorAll('.foo') would be preferable, though, as they are, indeed, better supported (93.99% vs 87.24%), according to caniuse.com:(正如yckart所建议的那样，根据caniuse.com的说法， querySelector('.foo')和querySelectorAll('.foo')会更好，因为它们的确受到了更好的支持（93.99％vs 87.24％）：)
querySelector(all)(querySelector（全部）)
getElementsByClassName(getElementsByClassName)
Don't use w3schools to learn something(不要使用w3schools学习东西)
Refer to MDN for accurate information(有关准确信息，请参考MDN)
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