String.prototype.slice()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
The slice()
method of String
values extracts a section of this string and
returns it as a new string, without modifying the original string.
Try it
Syntax
slice(indexStart)
slice(indexStart, indexEnd)
Parameters
indexStart
-
The index of the first character to include in the returned substring.
indexEnd
Optional-
The index of the first character to exclude from the returned substring.
Return value
A new string containing the extracted section of the string.
Description
slice()
extracts the text from one string and returns a new string.
slice()
extracts up to but not including indexEnd
. For example, str.slice(4, 8)
extracts the fifth character through the eighth character (characters indexed 4
, 5
, 6
, and 7
):
indexStart indexEnd ↓ ↓ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | | T | h | e | | m | i | r | r | o | r | m i r r _______________ ↑ Result
- If
indexStart >= str.length
, an empty string is returned. - If
indexStart < 0
, the index is counted from the end of the string. More formally, in this case, the substring starts atmax(indexStart + str.length, 0)
. - If
indexStart
is omitted, undefined, or cannot be converted to a number, it's treated as0
. - If
indexEnd
is omitted or undefined, or ifindexEnd >= str.length
,slice()
extracts to the end of the string. - If
indexEnd < 0
, the index is counted from the end of the string. More formally, in this case, the substring ends atmax(indexEnd + str.length, 0)
. - If
indexEnd <= indexStart
after normalizing negative values (i.e.indexEnd
represents a character that's beforeindexStart
), an empty string is returned.
Examples
Using slice() to create a new string
The following example uses slice()
to create a new string.
const str1 = "The morning is upon us."; // The length of str1 is 23.
const str2 = str1.slice(1, 8);
const str3 = str1.slice(4, -2);
const str4 = str1.slice(12);
const str5 = str1.slice(30);
console.log(str2); // he morn
console.log(str3); // morning is upon u
console.log(str4); // is upon us.
console.log(str5); // ""
Using slice() with negative indexes
The following example uses slice()
with negative indexes.
const str = "The morning is upon us.";
str.slice(-3); // 'us.'
str.slice(-3, -1); // 'us'
str.slice(0, -1); // 'The morning is upon us'
str.slice(4, -1); // 'morning is upon us'
This example counts backwards from the end of the string by 11
to find the
start index and forwards from the start of the string by 16
to find the end
index.
console.log(str.slice(-11, 16)); // "is u"
Here it counts forwards from the start by 11
to find the start index and
backwards from the end by 7
to find the end index.
console.log(str.slice(11, -7)); // " is u"
These arguments count backwards from the end by 5
to find the start index
and backwards from the end by 1
to find the end index.
console.log(str.slice(-5, -1)); // "n us"
Specifications
Specification |
---|
ECMAScript Language Specification # sec-string.prototype.slice |
Browser compatibility
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