break

嘗試一下

let i = 0; while (i < 6) { if (i === 3) { break; } i = i + 1; } console.log(i); // Expected output: 3 

語法

break [label]; 

label

可選的。欲中斷陳述句的標籤 (label) 識別。若不是要中斷迭代或 switch，則需加此參數。

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 。

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.

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.

block_1: { console.log('1'); break block_2; // SyntaxError: label not found } block_2: { console.log('2'); } 

規範

瀏覽器相容性

參見

• continue
• label
• switch