CODEWITHSUNDEEP
javascriptjqueryangularjs
sam
sam

Reputation: 698

Shorthand method to count length of array

I have an array like this

var arr = [{a:1, ...},{a:1, ...},{c:2, ...},{a:3, ...},{a:1, ...}]

how can I get the length of array where arr[x].a != 1 .

I know this can be done using for loop and push but I want to follow the best practise as every decent programmer should do.

P.S FYI I am using AngularJS.

EDIT 1 For anyone facing issues with arrow function in sajeetharan's answer because of ES6 script here is the solution

arr.filter(function(a){return a.a != 1}).length;

Upvotes: 15

Views: 3329

Answers (3)

Faly
Faly

Reputation: 13346

You can use array.prototype.filter and array.length:

var length = arr.filter(el => el.a !== 1).length

Upvotes: 15

Sajeetharan
Sajeetharan

Reputation: 222532

Use filter and length

const result = arrayToCount.filter(i => i.a != 1 ).length;

As @Naman Kheterpal mentioned below, Another way is to use reduce

const result = arrayToCount.reduce((c, o) => o + (o.a === 1), 0)

Upvotes: 21

Naman Kheterpal
Naman Kheterpal

Reputation: 1840

The most memory efficient way for this is:

const result = arr.reduce((count,el)=> count+ (el.a!==1)},0)

filter creates a complete new array, reduce only creates a new var. And both of them iterates over the array once.

Upvotes: 17

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