JavaScript: Pad (left, right) a string to get to a determined length

Last update on May 30 2022 10:02:08 (UTC/GMT +8 hours)

JavaScript String: Exercise-20 with Solution

Write a JavaScript function that can pad (left, right) a string to get to a determined length.

Test Data:
console.log(formatted_string('0000',123,'l'));
console.log(formatted_string('00000000',123,''));
Output:
"0123"
"12300000"

Pictorial Presentation:

JavaScript: Pad (left, right) a string to get to a determined

Sample Solution:-

HTML Code:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Write a JavaScript function that can pad (left, right) a string to get to a determined length.</title>
</head>
<body>

</body>
</html>

JavaScript Code:

function formatted_string(pad, user_str, pad_pos)
{
  if (typeof user_str === 'undefined') 
    return pad;
  if (pad_pos == 'l')
     {
     return (pad + user_str).slice(-pad.length);
     }
  else 
    {
    return (user_str + pad).substring(0, pad.length);
    }
}
console.log(formatted_string('0000',123,'l'));
console.log(formatted_string('00000000',123,''));

Sample Output:

0123
12300000

Flowchart:

Live Demo:

See the Pen JavaScript Pad (left, right) a string to get to a determined length - string-ex-20 by w3resource (@w3resource) on CodePen.

Improve this sample solution and post your code through Disqus

Previous: Write a JavaScript function to escape a HTML string.
Next: Write a JavaScript function to repeat a string a specified times.

JavaScript: Tips of the Day

How to insert an item into an array at a specific index (JavaScript)?

What you want is the splice function on the native array object.

arr.splice(index, 0, item); will insert item into arr at the specified index (deleting 0 items first, that is, it's just an insert). In this example we will create an array and add an element to it into index 2:

var arr = []; arr[0] = "Jani"; arr[1] = "Hege"; arr[2] = "Stale"; arr[3] = "Kai Jim"; arr[4] = "Borge"; console.log(arr.join()); arr.splice(2, 0, "Lene"); console.log(arr.join());

Ref: https://bit.ly/2BXbp04