Array conversion from string to int crashes the browser

Question

I am trying to convert an array of strings to an array of integers in javascript. I saw the following solution in a coupple of threads here and in a couple of other sources so I fuigure it must be correct, however when I get to the conversion the browser crashes. I have tried with Chromium and Firefox. Here is the source code, I am interested in what is causing this and what can be fixed:

 var str = "1,2,3,3,4,5,6";
 var arr1 = str.split(",");
 console.log(arr1);
  for(var k=0; k<=arr1.length; k++) { arr1[k] = +arr1[k]; }

KooiInc · Accepted Answer · 2014-05-07 13:17:03Z

1

In addition to the given answer, you may want to use this oneliner to create the array:

var arr1 = '1,2,3,4,5,6,7'.split(',').map(function(a){return +a;});

MDN page for Array.map

answered May 7, 2014 at 13:17

KooiInc

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Comments

thefourtheye · Accepted Answer · 2014-05-07 13:08:26Z

0

The problem is in this expression

k<=arr1.length

When k is 6, k++ increments k and it becomes 7. And then k <= arr1.length is true because arr1.length is 7. The next statement is

arr1[k] = +arr1[k];

which creates a new element in the array at index 7. So the array keeps on growing infinitely. What you should have done is

var arr1 = "1,2,3,3,4,5,6".split(",");
for (var k = 0; k < arr1.length; k++) {
    arr1[k] = +arr1[k];
}
console.log(arr1);
# [ 1, 2, 3, 3, 4, 5, 6 ]

Iterate only till the counter is lesser than length of the array. Otherwise store the length of the array in a temporary variable like this

for (var k = 0, len = arr1.length; k < len; k++) {
    arr1[k] = +arr1[k];
}

You can write the same as, simply

console.log("1,2,3,3,4,5,6".split(",").map(Number));
# [ 1, 2, 3, 3, 4, 5, 6 ]

edited May 7, 2014 at 13:08

answered May 7, 2014 at 13:03

thefourtheye

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2 Comments

VisioN Over a year ago

Also it is always better to save array length in the variable before actual iterations for not checking the length in each pass.

Stanimirovv Over a year ago

You are correct. It's a very stupid mistake. I hadn't noticed the extra "=" unitl you pointed it out. It took me a good amount of time looking too.

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