Getting Undefined when taking values out of an array

Question

I am trying to print individual values from an array but it doesn't seem to work (get undefined). When i print out the array itself it shows that values are contained in the array at index 0 and 1.

let imgDim = [];
imgDim.push(300);
imgDim.push(300);
let width = imgDim[0];
let height = imgDim[1];
let testString = "s994320";
if (/^[ms]\d+$/.test(testString) == true) {
    console.log(imgDim); //works
    console.log(width, height); //undefined undefined
}

If the syntax error in the declaration of `testString` is fixed (the value should be a quoted string), your code works properly. — Pointy, May 09 '19 at 13:20
@HereticMonkey if the actual code had that error, the first `console.log()` would not work. — Pointy, May 09 '19 at 13:21
oh sorry it is in my code but i forgot to add the .toString() here. I will just edit it. Thanks for pointing it out. — Ish Sah., May 09 '19 at 13:21
well if it works in that case then why does it not work here. Thats where i am confused. — Ish Sah., May 09 '19 at 13:28
@IshSah. your most recent edit does show the issue but it's *not* a problem with the array - it's because [the `load` callback is asynchronous](https://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call) — VLAZ, May 09 '19 at 13:41

score 2 · Accepted Answer · answered May 09 '19 at 13:20

It is error at let testString = s994320;

let imgDim = [];
imgDim.push(300);
imgDim.push(300);
let width = imgDim[0];
let height = imgDim[1];
let testString = 's994320';
if (/^[ms]\d+$/.test(testString) == true) {
  console.log(imgDim); //works
  console.log(width, height); //undefined undefined
}

let imgDim = [];
imgDim.push(300);
imgDim.push(300);
let width = imgDim[0];
let height = imgDim[1];
let testString = 's994320';
if (/^[ms]\d+$/.test(testString) == true) {
  console.log(imgDim); //works
  console.log(width, height); //undefined undefined
}

score 1 · Answer 2 · answered May 09 '19 at 13:21

by adding the quotes to s994320 the code works :

let imgDim = [];
imgDim.push(300);
imgDim.push(300);
let width = imgDim[0];
let height = imgDim[1];
let testString = "s994320";
if (/^[ms]\d+$/.test(testString) == true) {
  console.log(imgDim); //works
  console.log(width, height); //undefined undefined
}

score 0 · Answer 3 · answered May 09 '19 at 13:23

0

const imgDim = [];

imgDim.push(300);
imgDim.push(300);

const [
  width,
  height,
] = imgDim;

const testString = 's994320';

if (/^[ms]\d+$/.test(testString)) {
  console.log(imgDim);
  
  console.log(width, height);
}

answered May 09 '19 at 13:23

Orelsanpls

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Getting Undefined when taking values out of an array

3 Answers3