45 lines
913 B
Markdown
45 lines
913 B
Markdown
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---
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title: While Loop
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localeTitle: 而Loop
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---
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while循环首先评估条件。如果条件为真，则执行语句。如果条件为假，则不执行语句。之后，while循环结束。
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这是while循环的**语法** ：
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## 句法：
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```
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while (condition)
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{
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statement(s);
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}
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```
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_statement（s）：_只要条件求值为true就执行的语句。
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_condition：_这里，condition是一个布尔表达式，在每次循环之前计算。如果此条件的计算结果为true，则执行语句。当condition的计算结果为false时，继续执行while循环后的语句。
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## 例：
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```
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var i = 1;
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while (i < 10)
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{
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console.log(i);
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i++; // i=i+1 same thing
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}
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Output:
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1
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2
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3
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4
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5
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6
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7
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8
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9
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```
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_来源： [While Loop - MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/while)_
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