ruby - JavaScript Array: get "range" of items - Stack Overflow

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Is there an equivalent for ruby's array[n..m] in JavaScript?

For example:

>> a = ['a','b','c','d','e','f','g']
>> a[0..2]
=> ['a','b','c']

Is there an equivalent for ruby's array[n..m] in JavaScript?

For example:

>> a = ['a','b','c','d','e','f','g']
>> a[0..2]
=> ['a','b','c']

• javascript
• ruby
• arrays
• range

Share Improve this question Follow edited May 3, 2021 at 22:42 A-Sharabiani 19.3k2121 gold badges125125 silver badges137137 bronze badges asked Aug 26, 2010 at 23:08 shdevshdev 1,98544 gold badges1717 silver badges1818 bronze badges 1

• 3 yes, coffeescript! New-and-improved range, slice, splice and loop syntax. – Lance Pollard Commented May 18, 2011 at 23:02

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4 Answers 4

Sorted by: Reset to default 193

Use the array.slice(begin [, end]) function.

var a = ['a','b','c','d','e','f','g'];
var sliced = a.slice(0, 3); //will contain ['a', 'b', 'c']

The last index is non-inclusive; to mimic ruby's behavior you have to increment the end value. So I guess slice behaves more like a[m...n] in ruby.

The second argument in slice is optional, too:

var fruits = ['apple','banana','peach','plum','pear'];
var slice1 = fruits.slice(1, 3);  //banana, peach
var slice2 = fruits.slice(3);  //plum, pear

You can also pass a negative number, which selects from the end of the array:

var slice3 = fruits.slice(-3);  //peach, plum, pear

Here's the W3 Schools reference link.

a.slice(0, 3) Would be the equivalent of your function in your example.

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/slice

Ruby and Javascript both have a slice method, but watch out that the second argument to slice in Ruby is the length, but in JavaScript it is the index of the last element:

var shortArray = array.slice(start, end);

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