Converting string in array of Objects to an array of numbers

Question

I have an array of objects with some properties as string values, can someone help me to get array of numbers out it. Here is the array looks like.

  scores = [
               {
                  maxScore:"100"
                  obtainedScore:"79"
                  passed:"pass"
                  subject:"Maths"
               },
               {
                  maxScore:"100"
                  obtainedScore:"73"
                  passed:"pass"
                  subject:"Science"
               },
               {
                  maxScore:"100"
                  obtainedScore:"82"
                  passed:"pass"
                  subject:"English"
               }
           ]

i want obtainedScore and maxScore should be taken out from these objects and place them in two different arrays

i tried this

for (var  i =0 ; i < score.length; i++)
{ 
   var marks[i] = parseInt(score[i].obtainedScore) ;
}

and i found NaN.

As this is a pretty straightforward iteration of an array of objects, I'm wondering what code you have tried. — jfriend00
– jfriend00, Commented Aug 15, 2016 at 5:27
i tried this for (var i =0 ; i < score.length; i++){ var marks[i] = parseInt(score[i].obtainedScore; )} and i found NaN. — Gavishiddappa Gadagi
– Gavishiddappa Gadagi, Commented Aug 15, 2016 at 5:32
Put that code into your question. You should always show us what you have tried. — jfriend00
– jfriend00, Commented Aug 15, 2016 at 5:33
@GavisiddaGadagi probably that you refer to it as score when the declaration is scores. have a look at my answer which has a working snippet based on your attempt. — Iceman
– Iceman, Commented Aug 15, 2016 at 5:48
Cud Accept the answer that world and close the question if u solved the issue.. — Iceman
– Iceman, Commented Aug 15, 2016 at 7:02

Community · Accepted Answer · 2017-05-23 11:46:57Z

CORRECT ANSWER BASED ON YOUR ATTEMPT:

    var scores = [{
      maxScore: "100",
      obtainedScore: "79",
      passed: "pass",
      subject: "Maths"
    }, {
      maxScore: "100",
      obtainedScore: "73",
      passed: "pass",
      subject: "Science"
    }, {
      maxScore: "100",
      obtainedScore: "82",
      passed: "pass",
      subject: "English"
    }]
    var marks = [];
    for (var i = 0; i < scores.length; i++) {
      marks[i] = parseInt(scores[i].obtainedScore, 10);
    }
    console.log(marks)

MY SOLN (from before you editted in your attempt)

var scores = [{
      maxScore: "100",
      obtainedScore: "79",
      passed: "pass",
      subject: "Maths"
    }, {
      maxScore: "100",
      obtainedScore: "73",
      passed: "pass",
      subject: "Science"
    }, {
      maxScore: "100",
      obtainedScore: "82",
      passed: "pass",
      subject: "English"
    }]

    function decoupler(arr, prop) {
      return arr.map(function(item, index) {
        return parseInt(item[prop], 10);
      });
    }
    var arr1 = decoupler(scores, "maxScore");
    var arr2 = decoupler(scores, "obtainedScore");

    console.log(arr1);
    console.log(arr2);

Edit: Added radix parameter for parseInt() based on comment by jfriend00.

jfriend00 · Accepted Answer · 2016-08-15 22:12:01Z

1

what about mapping a projection?

var maxScores = scores.map(score => parseInt(score.maxScore, 10))
var obtainedScores = scores.map(score => parseInt(score.obtainedScore, 10))

edited Aug 15, 2016 at 22:12

jfriend00

711k104 gold badges1.1k silver badges1k bronze badges

answered Aug 15, 2016 at 5:32

user6716617

112 bronze badges

4 Comments

jfriend00 Over a year ago

You need to convert from string to number. I like the general simplicity of the approach though.

user6716617 Over a year ago

Oh, of course. completely overlooked that. if we assume the string represents a number, than it should be sufficient to add a 'parseInt'

jfriend00 Over a year ago

It's a good practice to include the radix argument when using parseInt(). Or you could just use score => +score.maxScore.

Iceman Over a year ago

@jfriend00 thanx. wasn't aware of this. was just reading thru mdn. so actually old browsers before es5 used to read "010" as 8 bcoz of earlier default: 8. Strange!! I've edited my answer as well. with the radix parameter as 10.

Nico · Accepted Answer · 2016-08-15 05:29:48Z

I am not 100% sure what you want the output to be but :

i want obtainedScore and maxScore should be taken out from these objects and place them in two different arrays

var arrScore = [],
        arrMax = [];

    scores.forEach(i => {
        arrScore.push(!isNaN(parseInt(i.obtainedScore)) ? parseInt(i.obtainedScore) : 0);
        arrMax.push(!isNaN(parseInt(i.maxScore)) ? parseInt(i.maxScore) : 0);
    });

Basically this creates two arrays arrScore which will contain each individual score value and arrMax which contains an array of the max scores.

Using the forEach function we iterate the array and push the values into their respective arrays. Note for this we are also ensuring that the type is a valid integer.

Dave · Accepted Answer · 2016-08-15 05:32:25Z

scores = [
               {
                  maxScore:"100",
                  obtainedScore:"79",
                  passed:"pass",
                  subject:"Maths"
               },
               {
                  maxScore:"100",
                  obtainedScore:"73",
                  passed:"pass",
                  subject:"Science"
               },
               {
                  maxScore:"100",
                  obtainedScore:"82",
                  passed:"pass",
                  subject:"English"
               }
           ];
           maxScoreArray = new Array();
           obtainedScoreArray = new Array();

           for (var i = scores.length - 1; i >= 0; i--) {
           	maxScoreArray.push(Number(scores[i].maxScore));
           	obtainedScoreArray.push(Number(scores[i].obtainedScore));
           }

           console.log(maxScoreArray);
           console.log(obtainedScoreArray);

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