<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>js arr_function</title>
</head>
<body>
<p id="demo"></p>
<button οnclick="f()">点我</button>
<script>
/*参考：https://www.cnblogs.com/1666818961-lxj/p/7404768.html*/
Array.prototype.upperCase = function () {
// this,代表Array.
for (let i = 0; i < this.length; i++) {
this[i] = this[i].toUpperCase();
}
};
function f() {
let fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.upperCase();
let demo = document.getElementById("demo");
demo.innerHTML = fruits;
// BANANA,ORANGE,APPLE,MANGO
}
</script>
</body>
</html>
