do...while
do...while
do...while语句
创建一个执行指定语句的循环,直到condition
值为 false。在执行statement
后检测condition
,所以指定的statement
至少执行一次。
语法
do
statement
while (condition
statement
执行至少一次的语句,并在每次condition
值为真时重新执行。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condition
值为真,statement
会再次执行。当condition
值为假,则跳到do...while
之后的语句。
示例
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。
HTML 内容
<div id="example"></div>
JavaScript 内容
var result = '';
var i = 0;
do {
i += 1;
result += i + ' ';
} while (i < 5
document.getElementById('example').innerHTML = result;
结果
规范
Specification | Status | Comment |
---|---|---|
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.2 |
ECMAScript 5.1 (ECMA-262)The definition of 'do-while statement' in that specification. | Standard | |
ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'do-while statement' in that specification. | Standard | Trailing ; is now optional. |
ECMAScript Latest Draft (ECMA-262)The definition of 'do-while statement' in that specification. | Living Standard | |
浏览器兼容性
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | 6 | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Edge | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |