JavaScript String slice()

slice() extracts part of a string and returns a new string. The start index is included and the end index is excluded. Negative indexes count backward from the end.

const text = "Welcome to www.plus2net.com";
console.log(text.slice(0, 7)); // Welcome

slice() Syntax Top ↑

string.slice(start)
string.slice(start, end)

Use Only a Start Index Top ↑

const text = "Welcome to www.plus2net.com";
console.log(text.slice(11)); // www.plus2net.com

When end is omitted, extraction continues to the end of the string.

Use Start and End Indexes Top ↑

const text = "JavaScript";
console.log(text.slice(0, 4)); // Java

The character at the end index is not included.

Negative Indexes Count from the End Top ↑

const text = "Welcome to www.plus2net.com";
console.log(text.slice(-1));      // m
console.log(text.slice(-4));      // .com
console.log(text.slice(-12, -4)); // plus2net

More slice() Examples from the Original Tutorial Top ↑

const text = "Welcome to www.plus2net.com";
console.log(text.slice(0, 7));   // Welcome
console.log(text.slice(11, 14)); // www
console.log(text.slice(0, -7));  // removes final 7 code units

slice() vs substring() Top ↑

Both use start and end indexes, but their negative-index behavior differs. slice() counts negative indexes from the end. substring() treats negative arguments as 0 and swaps the two arguments when the start is greater than the end.

slice() vs Legacy substr() Top ↑

substr() takes start, length, not start, end, and is a legacy feature. Prefer slice() or substring() in new code.

Extract Text After a Marker Top ↑

const email = "userid@example.com";
const at = email.indexOf("@");
const domain = email.slice(at + 1);
console.log(domain); // example.com

See the email string example and indexOf() tutorial for related techniques.

Common slice() Mistakes Top ↑

• Expecting the end index to be included.
• Confusing the second argument with a character count.
• Mixing up slice(), substring() and legacy substr().
• Forgetting negative indexes count from the end.
• Expecting slice() to modify the original string.

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Subhendu Mohapatra

Author & Instructor at plus2net

I write and maintain practical tutorials on Python, PHP, SQL, JavaScript, HTML, jQuery, and web development at plus2net. The tutorials focus on clear explanations, working examples, and code that readers can test and adapt while learning.

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