概览
do...while 语句创建了一个循环,该循环执行一个指定的语句直到condition 的值为 false. condition 在执行statement后才会被赋值,statement至少执行一次.
语法
do statement while (condition);
statement- 至少执行一次的语句,且只要condition值为true时,会再次执行. 想执行多行语句,可使用
block语句({ ... }) 包裹这些语句 .
condition- 循环中每次都会计算的表达式. 如果其值为true,statement会再次执行.当其值为false,则跳到
do...while 之后的语句.
示例
例子: 使用 do...while
下面的例子中, do...while 循环至少迭代一次,并且继续迭代直到 i 不再小于5时结束.
var i = 0;
do {
i += 1;
console.log(i);
} while (i < 5);
规范
| Specification | Status | Comment |
|---|---|---|
| ECMAScript 3rd Edition. | Standard | Initial definition. Implemented in JavaScript 1.2 |
| ECMAScript 5.1 (ECMA-262) do-while statement |
Standard | |
| ECMAScript 2015 (6th Edition, ECMA-262) do-while statement |
Standard | Trailing ; is now optional. |
浏览器兼容性
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | IE6+ | (Yes) | (Yes) |
| Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
|---|---|---|---|---|---|---|
| Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |