23 lines
1.2 KiB
Markdown
23 lines
1.2 KiB
Markdown
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---
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title: Iterate with JavaScript for Loops
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---
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The most common type of JavaScript loop is called a `for loop` because it runs `for` a specific number of times.
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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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ourArray will now contain [0,1,2,3,4]
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## More about for loops
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for(var i = 0; i < 5; i++) { // There are 3 parts here
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There are three parts to for loop. They are separated by semicolons.
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1. The initialization: `var i = 0;` - This code runs only once at the start of the loop. It's usually used to declare the counter variable (with `var`) and initialize the counter (in this case it is set to 0).
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2. The condition: `i < 5;` - The loop will run as long as this is `true`. That means that as soon as `i` is equal to 5, the loop will stop looping. Note that the inside of the loop will never see `i` as 5 because it will stop before then. If this condition is initially `false`, the loop will never execute.
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3. The increment: `i++` - This code is run at the end of each loop. It's usually a simple increment (`++` operator), but can really be any mathematical transformation. It is used to move the counter (`i`) forward (or backwards, or whatever.
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