Change empty values to NaN in Javascript array

Question

I have a Javascript array.

var myarray = ["100", "200", "", ""];

I am trying to change all blank values in the array to Number.NaN.

I can find examples online to change falsey values to 0, but I am not sure how to do it the other way around?

Empty strings are not null. I suggest you edit your title, it's misleading and incorrect. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… — Matt Morgan
– Matt Morgan, Commented Sep 26, 2020 at 16:06

Mahesh · Accepted Answer · 2020-09-26 17:27:50Z

1

Try using map function

const newArray=myarray.map(no=>{return parseInt(no)})

edited Sep 26, 2020 at 17:27

answered Sep 26, 2020 at 15:49

Mahesh

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3 Comments

Matt Morgan Over a year ago

parseInt should have a radix argument. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…

user3580480 Over a year ago

This doesn't work, the values in the array still show as "100", "200", "", ""

user12407908 Over a year ago

@user3580480" He gave an incomplete example and no explanation. What map does is it creates a new array based on the values of the original, and returns that array. So you need to assign its result to a variable. const newArray = myarray.map(...)

Nina Scholz · Accepted Answer · 2020-09-26 16:16:03Z

1

By having only strings, you could map with a default value.

var array = ["100", "200", "", ""];

array = array.map(v => v || NaN);

console.log(array);

answered Sep 26, 2020 at 16:16

Nina Scholz

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Comments

Matt Morgan · Accepted Answer · 2020-09-26 16:10:50Z

To change all the empty strings in your existing array in place to NaN, you can loop over the elements of the array:

var myarray = ["100", "200", "", ""];

for (let i = 0; i < myarray.length; i++){
  if (myarray[i] === "") {
    myarray[i] = NaN;
  }
}

console.log(myarray);

To return a new array with the empty strings replaced by NaN, you can use Array.map:

var myarray = ["100", "200", "", ""];

const newArray = myarray.map(el => el === "" ? NaN : el);

console.log(newArray);

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map

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