JavaScript substr()
JavaScript substr()
The substr()
method in JavaScript is used to extract a part of a string, starting from a specified position and for a specified length of characters. It can be used to retrieve a substring from the original string.
Syntax:
string.substr(start, length)
start
: Required. The position where to start the extraction from. A positive number represents the index of the character to start from, while a negative number represents the position from the end of the string. For example, -1 represents the last character of the string.length
: Optional. The number of characters to extract. If omitted, all characters from the start position to the end of the string will be extracted.
Examples:
Let's say we have a string "Hello, World!"
:
const str = "Hello, World!";
To extract the first 5 characters from the string, we can use:
const substr1 = str.substr(0, 5);
The value of substr1
will be "Hello"
.
To extract the last 6 characters from the string, we can use:
const substr2 = str.substr(-6);
The value of substr2
will be "World!"
.
Multiple ways to achieve the same result:
- We can also use the
slice()
method to achieve the same result. The syntax is similar tosubstr()
, except thatslice()
uses the end position instead of the length. - We can also use string indexing to extract substrings. For example,
str[0]
will give us the first character of the string, andstr[2]
will give us the third character of the string.
Overall, the substr()
method is a useful way to extract substrings from a larger string in JavaScript.