JavaScript/TypeScript: Concatenate string variables and string arrays with accordingly set spaces

Question

Situation
I want to concatenate string variables and string arrays in TypeScript like in this simple example:
// var1, var2: string
// arr1: string[]
const myString = 'result:' + var1 + ' ' + arr1.join(' ') + ' ' var2;

I don't want multiple spaces concatenated together and there shouldn't be any spaces at the end.
Problem
It is possible that those variables are set to '' or that the array is empty. These leads to multiple spaces concatenated together which I want to avoid.
Question
Is there a more elegant way to concatenate only the set variables separated with exactly one space?
Conditions

The solution should work with more variables/arrays
The solution should be a one-liner

SpoonMeiser · Accepted Answer

You can use destructuring to concatenate everything into a temporary array, and then use filter to remove any empty elements before calling join on the lot.


let var1 = "var1";
let arr1 = ["one", "", "two"];
let var2 = ""

const myString = "result:" + [var1, ...arr1, var2].filter(s => s).join(' ');

console.log(myString);

Pritam Kadam · Answer

Does this satisfy your requirements?
const strArr = ['result:' + var1, ...arr1, var2].map((a) => a.trim()).join(' ')

Update
As suggested, following handles

empty string
string with multiple spaces
trim additional spaces

const strArr = ['result:' + var1, ...arr1, var2].map((a) => a.trim()).filter(Boolean).join(' ')

Update 2
If you are using ES2019, you could do this in single pass:
const strArr = 
['result:' + var1, ...arr1, var2]
         .flatMap((el) => Boolean(el.trim()) ? [el.trim()] :[]).join(' ')

Robert Kossendey · Answer

You could try this:
const cleanedResult = result.replace(/ss+/g, ' ').trim()
This would remove multiple spaces in your variables as well though.
If you do not want that you can try out this solution:
const result = 'result:' + (var1 ? var1 + ' ' : '')  + (arr1 ? arr1.join(' ') : '') + (var2 ? var2 + ' ' : '')

JavaScript/TypeScript: Concatenate string variables and string arrays with accordingly set spaces

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