JavaScript数组前面插入元素代码

JS数组带有一个unshift方法可以再数组前面添加若干个元素，下面是详细的代码演示

<p id="demo">Click the button to add elements to the array.</p>
<button it</button>
<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon","Pineapple");
var x=document.getElementById("demo");
x.innerHTML=fruits;
}//codego.net/3/3/1/
</script>
<p><b>Note:</b> The unshift() method does not work properly in Internet Explorer 8 and earlier, the values will be inserted, but the return value will be <em>undefined</em>.</p>
执行后数组会变成下面的样子

Lemon,Pineapple,Banana,Orange,Apple,Mango

unshift在ie8及之前的版本工作有些问题，数组会插入元素，但是返回值是undefined