this 关键字用来将方法和属性绑定到一个对象的实例上
<script type="text/javascript">
/* 检查银行账户对象的构造函数*/
function Checking(amount) {
this.balance = amount; // 属性
this.deposit = deposit; // 方法
this.withdraw = withdraw; // 方法
this.toString = toString; // 方法
}
function deposit(amount) {
this.balance += amount;
}
function withdraw(amount) {
if (amount <= this.balance) {
this.balance -= amount;
}
if (amount > this.balance) {
alert("Insufficient funds");
}
}
function toString() {
return "Balance: " + this.balance;
}
var account = new Checking(500);
account.deposit(1000);
alert(account.toString()); //Balance: 1500
account.withdraw(750);
alert(account.toString()); // 余额: 750
account.withdraw(800); // 显示 " 余额不足 "
alert(account.toString()); // 余额: 750
</script>