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JS Strings - Properties and Methods

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James Hall
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Here is a collection of useful properties and methods that are used on Javascript strings. This is not an exhaustive list , rather it is a list of some of the ones that I have found most useful in my development.

A string is defined in JavaScript using the var keyword, like so:

var name = "John Doe";

A string can be anything inside either double or single quotes: "This is a string", but also 'so is this'.

Properties

length One of the properties that strings have in JS is the length property. It simply returns the number of characters in that string. To illustrate, we will use the name string that we created earlier.

name.length;             //returns 8

Methods

Strings have a vast number of methods.

charAt() This method returns the character that is at the specified index in the string. Note that JS uses zero-based counting, meaning that the first character is at the 0-index, the second character is at the 1-index, and so on.

name.charAt(0);             //returns "J"
name.charAt(1);             //returns "o"

charCodeAt() This method is similar to charAt() in that it returns the character at an index. This method, however, returns the unicode number for the character in that spot. In this case, the letter "J" has the unicode number 74.

name.charCodeAt(0);       //returns 74

concat() This method combines two or more strings. Note that it does not change any of the original strings; instead it returns a new string composed of the original strings.

var welcome = "Welcome ";
var greeting = ". Greetings."
welcome.concat(name);             //returns "Welcome John Doe"
welcome.concat(name, greeting);   //returns "Welcome John Doe. Greetings."

endsWith() Checks to see if a string ends with the specified characters. This method accepts multiple characters, as such:

name.endsWith('Doe');        //returns true

includes() Checks to see if a string is included in another string. This method is case sensitive.

name.includes("John");      //returns true

indexOf() Searches the string for the first occurrence of the specified value. If value is never found, it returns -1.

name.indexOf('o');        //returns 1
name.indexOf('w');        //returns -1

lastIndexOf() Searches the string for the last occurrence of the specified value. If value is never found, it returns -1.

name.lastIndexOf('o');        //returns 6
name.lastIndexOf('w');        //returns -1

match() Searches the string for the first match of a string using regular expressions. If the global flag is passed, it will return all matches of that string.

name.match(/o/);      //returns ["o", index: 1, input: "John Doe", groups: undefined]
name.match(/o/g);     //returns ["o", "o"]

search() Searches the string for the first occurrence of a specified value, and returns the index of that value. search() is different from indexOf() in that it can search for both regular expressions and simple strings.

name.search(/o/);     //returns 1    
name.match("o");      //returns 1
name.match("w");      //returns -1

slice() Extracts a segment from a larger string, returning the segment.

name.slice(0,4);     //returns "John"

split() Splits a string into an array of substrings based on a string.

name.split(" ");      //returns ["John", "Doe"]
name.split("o");      //returns ["J", "hn D", "e"]

For more information and guides on Javascript, check out the Mozilla Developer Network or W3Schools .

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