Lodash _.padStart() Method

What You’ll Learn

By the end of this tutorial, you’ll use Lodash’s _.padStart() confidently in real string workflows.

What Is _.padStart()?

_.padStart() prepends padding characters to the start of a string until it reaches the target length. It is the go-to helper for leading zeros on IDs, order numbers, and fixed-width codes.

📝 Syntax

_.padStart(string, [length=0], [chars=' '])

Syntax Rules

• string — The source string to pad on the left.
• length — Target total length (defaults to 0).
• chars — Optional fill string (default space).
• Return value — New left-padded string.
• Shorter strings — Returned unchanged when already >= length.

import padStart from "lodash/padStart";

const id = "42";
const formatted = padStart(id, 5, "0");
// -> "00042"

Examples Gallery

Practical _.padStart() patterns with copy-ready code and interactive Try It Yourself labs.

const original = "123";
const padded = _.padStart(original, 5, "0");

console.log(padded);
// -> "00123"

00123

const padded = _.padStart("hello", 10);
console.log(JSON.stringify(padded));
// -> "     hello"

"     hello"

const numbers = [10, 100, 1000, 10000];
const padded = numbers.map(n => _.padStart(String(n), 6, "0"));

console.log(padded);
// -> ["000010", "000100", "001000", "010000"]

["000010", "000100", "001000", "010000"]

const padded = _.padStart("world", 10, "-");
// -> "-----world"

-----world

const data = [
  { name: "John", age: 25 },
  { name: "Alice", age: 30 }
];

data.forEach(row => {
  console.log(_.padStart(row.name, 10) + _.padStart(String(row.age), 5));
});

      John   25
     Alice   30

const str = "123";
const native = str.padStart(5, "0");
const lodash = _.padStart(str, 5, "0");
// both -> "00123"

Both approaches yield: 00123

📝 Notes

• _.padStart() pads on the left only.
• Leading zeros for numeric strings is the most common use case.
• Default fill is a space when chars is omitted.
• Use _.padEnd() for right-side padding.
• Strings are immutable—assign the return value.
• Native String.padStart() covers the same behavior in modern JS.

💡 Best Practices