String.prototype.slice()
The slice()
method extracts a section of a string and
returns it as a new string, without modifying the original string.
Syntax
slice(beginIndex)
slice(beginIndex, endIndex)
Parameters
beginIndex
-
The zero-based index at which to begin extraction.
If
beginIndex
is negative,slice()
begins extraction fromstr.length + beginIndex
. (E.g."test".slice(-2)
returns"st"
)If
beginIndex
is omitted, undefined, or cannot be converted to a number (usingNumber(beginIndex)
),slice()
begins extraction from the beginning of the string. (E.g."test".slice()
returns"test"
)If
beginIndex
is greater than or equal tostr.length
, an empty string is returned. (E.g."test".slice(4)
returns""
) endIndex
Optional-
The zero-based index before which to end extraction. The character at this index will not be included.
If
endIndex
is omitted, undefined, or cannot be converted to a number (usingNumber(endIndex)
)slice()
extracts to the end of the string. (E.g."test".slice(2)
returns"st"
)If
endIndex
is greater thanstr.length
,slice()
also extracts to the end of the string. (E.g."test".slice(2, 10)
returns"st"
)If
endIndex
is negative,slice()
treats it asstr.length + endIndex
. (E.g, ifendIndex
is-2
, it is treated asstr.length - 2
and"test".slice(1, -2)
returns"e"
) .If
endIndex
represents a position that is before the one represented bystartIndex
,slice()
returns""
. (E.g"test".slice(2, -10)
,"test".slice(-1, -2)
or"test".slice(3, 2)
).
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.
Changes to the text in one string do not affect the other string.
slice()
extracts up to but not including endIndex
.
str.slice(1, 4)
extracts the second character through the fourth
character (characters indexed 1
, 2
, and 3
).
As an example, str.slice(2, -1)
extracts the third character
through the second to last character in the string.
Examples
Using slice()
to create a new string
The following example uses slice()
to create a new string.
let str1 = 'The morning is upon us.', // the length of str1 is 23.
str2 = str1.slice(1, 8),
str3 = str1.slice(4, -2),
str4 = str1.slice(12),
str5 = str1.slice(30);
console.log(str2) // OUTPUT: he morn
console.log(str3) // OUTPUT: morning is upon u
console.log(str4) // OUTPUT: is upon us.
console.log(str5) // OUTPUT: ""
Using slice()
with negative indexes
The following example uses slice()
with negative indexes.
let str = 'The morning is upon us.'
str.slice(-3) // returns 'us.'
str.slice(-3, -1) // returns 'us'
str.slice(0, -1) // returns 'The 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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