When i try to put an array into a JavaScript array, a la,

> `${[1,2,3]}`

I get back this

'1,2,3'

and not

'[1,2,3]'

in the latest Node & Chrome.

I am missing something incredibly obvious, but need it spelled out to me nevertheless : )

When i try to put an array into a JavaScript array, a la,

> `${[1,2,3]}`

I get back this

'1,2,3'

and not

'[1,2,3]'

in the latest Node & Chrome.

I am missing something incredibly obvious, but need it spelled out to me nevertheless : )

• javascript
• ecmascript-6

• 3 developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Andrew Li Commented Jun 14, 2017 at 13:51
• You are getting the string interpretation of an array, so a join with comma separated values, change it to `[${[1, 2, 3]}]` should do it – Icepickle Commented Jun 14, 2017 at 13:52
• 1 what ever object you use, its toString() gets called. Array.toString() returns a string of comma separated items of the array. – bugs_cena Commented Jun 14, 2017 at 14:12
• I'm missing why you would expect this to get that non-obvious result? Template literals are not JSON.stringify. – Bergi Commented Jun 14, 2017 at 17:28

3 Answers 3

You should use JSON.stringify(array) It can help you to predict conversion to the string any arrays in this array.

const array = [["expected","test",1],0];
const arrayStr = JSON.stringify(array);
const templateResAsString = `${array}`; // expected,test,1,0
const templateResAsarray = `${arrayStr}`; // [["expected","test",1],0]

By the default, the values that are interpolated into a template literal are converted to their string representation.

For objects that means calling their .toString() method. The string representation of an array is simply a comma separated list of the strings representation of its elements, without leading [ or trailing ]:

console.log(
  [1,2,3].toString()
);

Consolodiated list including above answers:

const arr = [1,2,3,4,5,'foo','bar','baz']


console.log(JSON.stringify(arr));
console.log(JSON.stringify(arr, null, 2));
console.log(arr.toString());
console.log(`${arr}`);
console.log(arr.join('\n'));

Good Luck...