Javascript String padStart()

The JavaScript String padStart() method pads the current string with another string to the start.

The syntax of the padStart() method is:

str.padStart(targetLength, padString)

Here, str is a string.


padStart() Parameters

The padStart() method takes in:

  • targetLength - The length of the final string after current string has been padded. For targetLength < str.length, the string is returned unmodified.
  • padString (optional) - The string to pad current string with. Its default value is " ".

Note: If padString is too long, it will be truncated from the end to meet targetLength.


Return value from padStart()

  • Returns a String of the specified targetLength with padString applied from the start.

Example: Using padStart()

let string = "CODE";

value1 = string.padStart(10);
console.log(value1); // "      CODE"

value2 = string.padStart(10, "*");
console.log(value2); // "******CODE"

// long string is truncated
value3 = string.padStart(10, "ABCDEFGHIJKL");
console.log(value3); // "ABCDEFCODE"

function fixedLength(num, len) {
  return num.toString().padStart(len, 0);
}

price = fixedLength(5000, 6);
console.log("$" + price); // "$005000"

Output

      CODE
******CODE
ABCDEFCODE
$005000

Recommended Reading: JavaScript String padEnd()