Substring Examples
This page was last reviewed on Dec 13, 2023.
Dot Net Perls
Substring. A string has 10 characters, but we wantonly a part of this string—the first 5, the last 3. With substring we get a string from within an existing string.
In Node.js, substring receives 2 arguments: the first index of the substring we are trying to take, and the last index. The second argument is not a count.
First example. Let us begin with this example. We have an input string "cat123." To get the "cat" part, we use a first index of 0, and a last index of 3.
Argument 1 The index of the first char we are taking a substring at—the first char in a string is at index 0.
Argument 2 The last index of the substring. This is not a count, but rather another position in the string.
var value = "cat123"; console.log("VALUE: " + value); // Take a substring of the first 3 characters. // ... Start at index 0. // ... Continue until index 3. var result = value.substring(0, 3); console.log("SUBSTRING: " + result);
VALUE: cat123 SUBSTRING: cat
Substring, 1 argument. Substring can be used with just 1 argument. This is the start index. We can think of this argument as the number of characters we want to skip over.
Info For substring with 1 argument, the remaining part of the string (after the index specified) is included.
var value = "x_frog"; // Skip over first 2 characters. var result = value.substring(2); console.log("VALUE: " + value); console.log("SUBSTRING: " + result);
VALUE: x_frog SUBSTRING: frog
With substring, we have a way to extract parts of strings. For optimal performance, using the original string and not changing it at all is best, but this is not always possible.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Dec 13, 2023 (edit).
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