break
嘗試一下
語法
說明
中斷陳述 break
可加上標籤 (label) 參數,使其跳出被標籤的陳述語句。此中斷陳述 break
必須被包含在被標籤的陳述語句中。被標籤的陳述語句可被添加於任一個區塊 (block) 前,而非限定在迴圈陳述。
範例
下面函式包含一個中斷陳述 break
,當 i
值為 3 時,中斷 while
迴圈,並回傳 3 * x
。
js
function testBreak(x) {
var i = 0;
while (i < 6) {
if (i == 3) {
break;
}
i += 1;
}
return i * x;
}
The following code uses break
statements with labeled blocks. A break
statement must be nested within any label it references. Notice that inner_block
is nested within outer_block
.
js
outer_block: {
inner_block: {
console.log("1");
break outer_block; // breaks out of both inner_block and outer_block
console.log(":-("); // skipped
}
console.log("2"); // skipped
}
The following code also uses break
statements with labeled blocks but generates a Syntax Error because its break
statement is within block_1
but references block_2
. A break
statement must always be nested within any label it references.
js
block_1: {
console.log('1');
break block_2; // SyntaxError: label not found
}
block_2: {
console.log('2');
}
規範
Specification |
---|
ECMAScript Language Specification # sec-break-statement |
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