CODEWITHSUNDEEP
javascriptarrays
deyn80
deyn80

Reputation: 9

how can i divide numeric elements in an array while keeping the values of non-numeric ones

given this array ['1', 23, null, 46.5, '34e2', , false, 'true', , 40], how can i divide the numeric elements in it by 10, but also keeping the non numeric elements in it, without modifying those values. what i did so far is this:

var divide = numbers.map(function(x){
    if(typeof x === 'number' && isFinite(x)){
    return x / 10;
    }
});

console.log(divide); // [undefined, 2.3, undefined, 4.65, undefined, 6: undefined, 7: undefined, 9: 4]

Upvotes: 0

Views: 73

Answers (3)

Rahul Gaba
Rahul Gaba

Reputation: 480

You are returning the the numerical value but you are not handling the case if x isn't a number just add return x after the if condition and it would work perfectly :)

var divide = numbers.map(function(x){
    if(typeof x === 'number' && isFinite(x)){
      return x / 10;
    }
    return x;
});

Upvotes: 2

David Thomas
David Thomas

Reputation: 253446

The problem is that Array.prototype.map() will return a value from the anonymous function performed on each iteration over the Array, and without a specific value to be returned it will – as will any JavaScript function – simply return undefined if a specific value isn't provided to be returned (as you found out); so the key is to return the current value if that value doesn't match the conditions of the if assessment.

var numbers = ['1', 23, null, 46.5, '34e2', , false, 'true', , 40],
  divide = numbers.map(function(x) {
    if ('string' === typeof x && isFinite(x)) {
      return x / 10;
    } else {
      return x;
    }
  });

console.log(divide);

Incidentally, as you're not using this anywhere, and if ES6` is an option for you, and your users, you could also use Arrow functions:

var numbers = ['1', 23, null, 46.5, '34e2', , false, 'true', , 40],
  divide = numbers.map(x => 'string' === typeof x && isFinite(x) ? x/10 : x);

console.log(divide);

References:

Upvotes: 2

TimoStaudinger
TimoStaudinger

Reputation: 42490

Your mapping function has to return a value for each of the elements, not only the numeric ones:

var divide = numbers.map(function(x){
    if(typeof x === 'number' && isFinite(x)){
        return x / 10;
    } else return x;
});

Upvotes: 3

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