JavaScript Strings

JavaScript String slice

Written by Swapnil RajaPublished 24 Aug 2026

slice takes a piece out of a string without changing the original.

It works just like slice on an array.

The end index is not included, which catches people out.

Example

javascript

const text = "JavaScript";

console.log(text.slice(0, 4));
console.log(text.slice(4));

The output is Java then Script.

Taking Pieces

slice(start, end) returns the characters from start up to but not including end.

Leaving out the end takes everything to the finish.

Negative numbers count from the end.

Syntax

javascript

text.slice(start, end);

The original string is never changed.

Negative Indexes

This is the easiest way to take the last few characters.

Example

javascript

const file = "report.pdf";

console.log(file.slice(-3));
console.log(file.slice(0, -4));

The output is pdf then report.

slice and substring

substring is similar but treats negatives as 0.

slice is usually the one you want.

Example

javascript

const text = "JavaScript";

console.log(text.slice(-6));
console.log(text.substring(-6));

substring ignored the negative and returned everything.

A Single Character

charAt, brackets and at all work.

Example

javascript

const text = "hello";

console.log(text.charAt(1));
console.log(text[1]);
console.log(text.at(-1));

at is the only one that accepts a negative index.

Splitting a Name

Combining indexOf with slice is a common pattern.

Example

javascript

const full = "Ada Lovelace";
const space = full.indexOf(" ");

console.log(full.slice(0, space));
console.log(full.slice(space + 1));

split does this more directly, as the next lessons show.

Shortening Text

Adding an ellipsis when the text is too long.

Example

javascript

function shorten(text, max) {
  return text.length <= max ? text : text.slice(0, max) + "...";
}

console.log(shorten("A very long title", 6));
console.log(shorten("Short", 6));

Only the first was long enough to be cut.

Complete Example

html

<!DOCTYPE html>
<html>
<head>
  <title>JavaScript String slice</title>
</head>
<body>

  <h1>String slice</h1>

  <p id="out"></p>

  <script>
    const text = "JavaScript Basics";

    document.getElementById("out").innerHTML =
      "First word: " + text.slice(0, text.indexOf(" ")) +
      "<br>Last six: " + text.slice(-6) +
      "<br>Shortened: " + text.slice(0, 10) + "...";
  </script>

</body>
</html>

Try It Yourself

Run the above example in the Try It Editor.

Try different numbers:

Change the slice positions and watch the pieces change.

Important Points

slice(start, end) excludes the end index.
Leaving out the end takes the rest of the string.
Negative indexes count from the end.
substring treats negatives as 0.
The original string is never changed.

Conclusion

slice is the everyday tool for taking part of a string.

Negative indexes make working from the end easy.

Prefer it to substring, which behaves less predictably.

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