Replace all left spaces with a specific string

Question

I have following code to replace left spaces with a specific string but, It is not working as I want.

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Answer 1

This will surely do in two lines:

  var str ='   asdadasdad as asdasd asasd';   
  console.log(str.trim().padStart(str.length, 'x')); 

Answer 2

You may use a lambda function as 2nd argument of .replace:

const s = '  asdadasdad as asdasd asasd';

var repl = s.replace(/^\s+/, m => m.replace(/\s/g, 'x'));

console.log(repl);

Answer 3

Currently you're replacing complete match with single x character but you need to repeat x to length of match,

let str = '  asdadasdad as asdasd asasd'
let replacedStr = str.replace(/^\s+/, (m) => 'x'.repeat(m.length))
console.log(replacedStr)

Answer 4

You may use

.replace(/\s/gy, 'x')

Here, each whitespace that is at the start of the string is replaced with x. The combination of the g (global) and y (sticky) modifiers makes it match at the start of the string, and then consecutively until no match is found.

JS demo:

console.log(
  '  asdadasdad as asdasd asasd'.replace(/\s/gy, 'x')
)

Answer 5

You can use a callback function to generate the same length string which contains x.

console.log('  asdadasdad as asdasd asasd'.replace(/^\s+/, m => new Array(m.length).fill('x').join('')))

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Or alternately with positive look-behind(not supported widely, check here).

    console.log('  asdadasdad as asdasd asasd'.replace(/(?<=^\s*)\s/g, 'x'))