String methods in javascript

4 min readJul 16, 2021

The string object in javascript comes with a bunch of built-in methods that are useful when working this this type of data. So let’s take a look at the main methods and learn a bit about them.

concat( )

The concat() method concatenates the string arguments to the calling string and returns a new string.

endsWith( )

The endsWith() method determines whether a string ends with the characters of a specified string, returning true or false as appropriate.

includes( )

The includes() method performs a case-sensitive search to determine whether one string may be found within another string, returning true or false as appropriate.

indexOf( )

The indexOf() method returns the index within the calling String object of the first occurrence of the specified value, starting the search at fromIndex. Returns -1 if the value is not found.

lastIndexOf( )

The lastIndexOf() method returns the index within the calling String object of the last occurrence of the specified value, searching backwards from fromIndex. Returns -1 if the value is not found.

repeat( )

The repeat() method constructs and returns a new string which contains the specified number of copies of the string on which it was called, concatenated together.

replace( )

The replace() method returns a new string with some or all matches of a pattern replaced by a replacement. The pattern can be a string or a RegExp, and the replacement can be a string or a function to be called for each match. If pattern is a string, only the first occurrence will be replaced.

slice( )

The slice() method extracts a section of a string and returns it as a new string, without modifying the original string.

split( )

The split() method divides a String into an ordered list of substrings, puts these substrings into an array, and returns the array. The division is done by searching for a pattern; where the pattern is provided as the first parameter in the method's call.

startsWith( )

The startsWith() method determines whether a string begins with the characters of a specified string, returning true or false as appropriate.

substring( )

The substring() method returns the part of the string between the start and end indexes, or to the end of the string.

toLowerCase( )

The toLowerCase() method returns the calling string value converted to lower case.

toUpperCase( )

The toUpperCase() method returns the calling string value converted to uppercase (the value will be converted to a string if it isn't one).

trim( )

The trim() method removes whitespace from both ends of a string. Whitespace in this context is all the whitespace characters (space, tab, no-break space, etc.)