Convert Javascript array of single-element arrays into 1d array

Question

I'm stumped with this one. I have an array that looks like this:

[[1],[2],[3],[4],[5]]

(an array of single member arrays)

That array is given to me by google apps script, so I can't change the code that creates it.

i'm trying to get the index of a certain value. I can't use indexOf because each value is an array of a single member (I tried array.indexOf([3]), but that doesn't work). Is there an easy way to convert it to a 1d array like this:

[1,2,3,4,5]

I could always loop over the members of the original array, and copy it to a new array, but it seems like there should be a better way.

Possible duplicate of Merge/flatten an array of arrays in JavaScript? — OJay
– OJay, Commented Jan 18, 2017 at 0:58

charlietfl · Accepted Answer · 2017-01-18 00:56:24Z

1

Just use map()

var newArr = data.map(function(subArr){
  return subArr[0];
})

answered Jan 18, 2017 at 0:56

charlietfl

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MT0 · Accepted Answer · 2017-01-18 01:03:45Z

1

You can use reduce():

var a = [[1],[2],[3],[4],[5]];
var b = a.reduce( function( prev, item ){ return prev.concat( item ); }, [] );
console.log(b);

Or concat:

var a = [[1],[2],[3],[4],[5]];
var b = Array.prototype.concat.apply([], a );
console.log(b);

Or map:

var a = [[1],[2],[3],[4],[5]];
var b = a.map( function(item){ return item[0]; } );
console.log(b);

answered Jan 18, 2017 at 1:03

MT0

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poushy · Accepted Answer · 2017-01-18 00:58:09Z

0

You can try to use map, which is similar to looping, but much cleaner:

arr.map(function(val){return val[0];});

Or filter to directly filter the value you need:

var num = 1;
arr.filter(function(val){return val[0] == num;});

answered Jan 18, 2017 at 0:58

poushy

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Analytical360 · Accepted Answer · 2017-01-18 00:58:01Z

0

Found one answer, that seems simple enough, so I thought I would share it:

  var a = [[1], [2], [3], [4], [5], [6], [7]];
  var b = a.map(function(value, index){return value[0];});

answered Jan 18, 2017 at 0:58

Analytical360

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Patrick Murphy · Accepted Answer · 2017-01-18 00:58:28Z

0

Here is a one liner that will do it:

array.toString().split(',').map(Number);

answered Jan 18, 2017 at 0:58

Patrick Murphy

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