40 lines
1.5 KiB
Markdown
40 lines
1.5 KiB
Markdown
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---
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title: JavaScript for Loops Explained
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---
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The for statement creates a loop that consists of three optional expressions, enclosed in parentheses and separated by semicolons, followed by a statement or a set of statements executed in the loop.
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The for loop has the following syntax:
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for (<a href='http://forum.freecodecamp.com/t/javascript-while-loop/14668' target='_blank' rel='nofollow'>initialization]; [condition]; [final-expression]) {
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code block to be executed
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}
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[initialization] is executed before the loop (the code block) starts.
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[condition] defines the condition for running the loop (the code block).
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[final-expression] is executed each time after the loop (the code block) has been executed.
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## Example in JavaScript:
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var ourArray = [];
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for (var i = 0; i < 5; i++) {
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ourArray.push(i);
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}
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From the example above, you can read:
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[initialization] sets a variable before the loop starts (var i = 0).
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[condition] defines the condition for the loop to run (i must be less than 5).
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[final-expression] increases a value (i++) each time the code block in the loop has been executed.
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## Why we need "for loops"?
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For loops are used to loop through a block of code a known number of times. Sometimes it is the computer that knows how many times, not you, but it is still known.
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Checkout some of our other articles on loops:
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* [While Loop</a>
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* <a href='http://forum.freecodecamp.com/t/javascript-for-in-loop/14665' target='_blank' rel='nofollow'>For In Loop</a>
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