concat empty / single item array

Question

Ok, so I have this simple code :

for(var i=0; i<lines.length; i++) {
    elements += myFunction(lines[i]);
}

Where elements is an empty array at the start and myFunction() is just a function that returns an array of strings.

The problem is that if myFunction() returns an array with a single string, the += is interpreted as a string concat in place of an array concat. At the end of the loop the result is just a long string and not an array.

I tried push()ing the values in place of concatenation, but this just gives me a two dimensional matrix with single item arrays.

How can I solve this typecasting problem ? Thank you in advance !

Plz give some code , what have you tried and some example would be handful to help you. — ameya rote
– ameya rote, Commented Dec 18, 2012 at 6:46
Show some (minimal) sample input and what you want as output. — RobG
– RobG, Commented Dec 18, 2012 at 6:47

Amber · Accepted Answer · 2012-12-18 06:47:09Z

1

Try :

 for(var i=0; i<lines.length; i++) {
        elements [i] = myFunction(lines[i]);
    }

I suppose it solves the problem.

answered Dec 18, 2012 at 6:47

Amber

1,24913 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

m_vdbeek Over a year ago

Thanks this solved the problem. You just have to change lines[i] into lines[0]

John Flatness · Accepted Answer · 2012-12-18 06:47:52Z

1

You can use the Array concat function:

elements = elements.concat(myFunction(lines[i]));

answered Dec 18, 2012 at 6:47

John Flatness

34.1k5 gold badges81 silver badges81 bronze badges

2 Comments

m_vdbeek Over a year ago

actually concat returns an empty array

John Flatness Over a year ago

[].concat(['some-string']) equals ['some-string'], which I'm pretty sure is the desired output you described. Are you assigning the result of concat (it doesn't modify the array, it returns a new one)?

RobG · Accepted Answer · 2012-12-18 06:53:28Z

0

Presumably you want something like:

var arrs = [[0],[1,2],[3,4,5],[6]];
var result = [];

for (var i=0, iLen=arrs.length; i<iLen; i++) {
  result = result.concat(arrs[i]);
}

alert(result); // 0,1,2,3,4,5,6

Ah, you want to concatenate the results of a function. Same concept, see other answers.

answered Dec 18, 2012 at 6:53

RobG

148k32 gold badges180 silver badges216 bronze badges

Comments

zafus_coder · Accepted Answer · 2012-12-18 06:56:25Z

0

You can also use myArray[myArray.length] = someValue;

answered Dec 18, 2012 at 6:56

zafus_coder

4,6312 gold badges14 silver badges13 bronze badges

1 Comment

Yytsi Over a year ago

Actually, that would assign the item outside of the bounds. myArray.length - 1 would be the index of the last element instead.

mynameistechno · Accepted Answer · 2016-08-10 05:46:12Z

0

let newArray = [].concat(singleElementOrArray)

answered Aug 10, 2016 at 5:46

mynameistechno

3,5631 gold badge39 silver badges32 bronze badges

Collectives™ on Stack Overflow

concat empty / single item array

5 Answers 5

1 Comment

2 Comments

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

1 Comment

2 Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related