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JavaScript String Methods


String Methods String Methods
String length String slice()
String substring() String substr()
String replace() String replaceAll()
String toLowerCase() String concat()
String trim() String trimStart()
String trimEnd() String padStart()
String padEnd() String charAt()
String charCodeAt() String split()

Note


String search methods are covered in the next chapter.

JavaScript String Length

  The length property returns the length of a string:

Example

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let text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
let length = text.length;

Extracting String Parts

There are 3 methods for extracting a part of a string:

  slice(start, end)

  substring(start, end)

  substr(start, length)

JavaScript String slice()

slice() extracts a part of a string and returns the extracted part in a new string.
The method takes 2 parameters: start position, and end position (end not included).

Example

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Slice out a portion of a string from position 7 to position 13:

let text = "Apple, mango, orange";
let part = text.slice(7, 13);

Note


JavaScript counts positions from zero.

First position is 0.

Second position is 1.

Example

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If you omit the second parameter, the method will slice out the rest of the string:

let text = "Apple, mango, orange";
let part = text.slice(7);

Example

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If a parameter is negative, the position is counted from the end of the string

let text = "Apple, Banana, Kiwi";
let part = text.slice(-12);

Example

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This example slices out a portion of a string from position -12 to position -6:

let text = "Apple, Banana, Kiwi";
let part = text.slice(-12, -6);

JavaScript String substring()

substring() is similar to slice().
The difference is that start and end values less than 0 are treated as 0 in substring().

Example

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let str = "Apple, Banana, Kiwi";
let part = str.substring(7, 13);

If you omit the second parameter, substring() will slice out the rest of the string.


JavaScript String substr()

substr() is similar to slice().
The difference is that the second parameter specifies the length of the extracted part.

Example

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let str = "Apple, Banana, Kiwi";
let part = str.substr(7, 6);

If you omit the second parameter, substr() will slice out the rest of the string.

Example

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let str = "Apple, Banana, Kiwi";
let part = str.substr(7);

If the first parameter is negative, the position counts from the end of the string.

Example

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let str = "Apple, Banana, Kiwi";
let part = str.substr(-4);