Useful String Methods In JavaScript.

Strings are useful for holding data that can be represented in text form. Some of the most-used operations on strings are to check their length, to build and concatenate them using the + and += string operators, checking for the existence or location of substrings with the indexOf() method, or extracting substrings with the substring() method.

Finding the length of a string.

The length property is used to find the length of a string.

let str = 'phpforever';
console.log(str.length)

Output : 10

Finding a substring inside a string and extracting it.

The indexOf() method returns the index of (the position of) the first occurrence of a specified text in a string.

var str ="Find a string inside the string";
var pos = str.indexOf("string");

Output : 7

The lastIndexOf() method returns the index of the last occurrence of a specified text in a string.

var str = "Find a string inside the string";
var pos = str.lastIndexOf("string");

Output:25

Searching for a String in a String.

The search() method searches a string for a specified value and returns the position of the match.

var str = "Find a string inside the string";
var pos = str.search("string");

Output : 7.

Extracting String Parts.

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

• slice(start, end)
• substring(start, end)
• The slice() Method

The slice() Method.

slice() extracts a part of a string and returns the extracted part in a new string.

The method takes 2 parameters: the start position, and the end position (end not included).

Example.

var str = "Apple, Banana, Kiwi";
var res = str.slice(7, 13);

Output : Banana.

The substring() Method.

substring() is similar to slice(). The difference is that substring() cannot accept negative indexes.

var str = "Apple, Banana, Kiwi";

var res = str.substring(7, 13);

The substr() Method.

substr() is similar to slice().

The difference is that the second parameter specifies the length of the extracted part.

str = "Please visit phpforever!";
var n = str.replace("phpforever", "forever");

Converting to Upper and Lower Case.

A string is converted to upper case with toUpperCase().

var text1 = "Hello World!"; 
var text2 = text1.toUpperCase();

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