<!DOCTYPE html>
<html lang="en"><head> <meta charset="UTF-8"> <title>map的用法</title></head><body><p id="demo"></p><script>var numbers = [4,9,16,25];function myFunc(){ var demo = document.getElementById('demo'); demo.innerHTML = numbers.map(Math.sqrt);//2,3,4,5}// myFunc();var demo = document.getElementById('demo');
numbers.map( function (item,index,arr){ arr[index] = item*item; demo.innerHTML = arr; });</script>
</body></html>