Question

26

How to sum an array of strings, representing ints

rated 0 times [ 29] [ 3] / answers: 1 / hits: 16099 / 12 Years ago, mon, october 29, 2012, 12:00:00

How to sum such an Array
[ '', '4490449', '2478', '1280990', '22296892', '244676', '1249', '13089', '0', '0', '0n' ]

If I call something like that ['','4490449', ... , '0n' ].reduce(function(t,s){ return t+s) on that array, the stings are joined and not summed.

I've tried some casting with parseInt() but this results in NaN :)

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hailey

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3 Years ago

answered 12 Years ago faithemilys · Accepted Answer

You need to assure that the values you are summing are integers. Here's one possible solution:

var ary=[ '', '4490449', '2478', '1280990', '22296892', 

          '244676', '1249', '13089', '0', '0', '0n' ];



console.log(

  ary

    .map( function(elt){ // assure the value can be converted into an integer

      return /^d+$/.test(elt) ? parseInt(elt) : 0; 

    })

    .reduce( function(a,b){ // sum all resulting numbers

      return a+b

    })

);

which prints '28329823' to the console.

See fiddle at http://jsfiddle.net/hF6xv/