ES6 Strings

JavaScript string is an object which represents the sequence of characters. Generally, strings are used to hold text-based values such as a person name or a product description.

In JavaScript, any text within the single or double quotes is considered as a string. There are two ways for creating a string in JavaScript:

• By using a string literal
• By using string object (using the new keyword)

Let us elaborate both ways of creating a string in JavaScript.

By using a string literal

The string literals can be created by using either double quotes or by using single quotes. The syntax for creating string literal is given below:

var stringname = "string value";

By using String object (using the new keyword)

Here, we will use a new keyword for creating the string object. The syntax for creating the string object is given below:

var stringname = new String ("string literal");

String Properties

There are some properties of the string that are tabulated as follows:

Let us discuss the above string properties in detail.

The constructor property returns the constructor function for an object. Instead of the name of the function, it returns the reference of the function.

string.constructor

var str = new String("Hello World");
console.log("Value of str.constructor is: "+str.constructor);

As its name implies, this property returns the number of characters or the length of the string.

string.length

var str = new String("Hello World");
console.log("The number of characters in the string str is: "+str.length);

It allows us to add new methods and properties in an existing object type. It is a global property which is available with almost all the objects of JavaScript.

object.prototype.name = value;

function student(name, qualification){
this.name = name;
this.qualification = qualification;
}
student.prototype.age = 20;
var stu = new student('Daniel Grint' , 'BCA');
console.log(stu.name);
console.log(stu.qualification);
console.log(stu.age);

ES6 String Methods

There are four string functions available in ES6, which are tabulated as follows:

Let us discuss the above string methods in detail.

It is a case-sensitive method, which determines whether the string begins with the specified string characters or not. It returns true if the string begins with the characters and returns false if not.

string.startsWith(searchValue, startPosition)

This method includes two parameters that are as follows:

• searchValue: It is the required parameter of this method. It includes the characters to be searched for at the start of the string.
• startPosition: It is an optional parameter. Its default value is 0. It specifies the position in the string at which to begin searching.

var str = 'Welcome to rookienerd :)'; 
console.log(str.startsWith('Wel',0));
console.log(str.startsWith('wel',0));

It is also a case-sensitive method that determines whether a string ends with the characters of the specified string or not.

string.endsWith(searchvalue, length)

The parameters of this method are defined as follows:

• searchValue: It is the required parameter that represents the characters to be searched at the end of the string.
• length: It is an optional parameter. It is the length of the string that will be searched. If this parameter is omitted, then the method will search in the full length of the string.

var str = "Welcome to rookienerd.";
console.log(str.endsWith("to", 10))
console.log(str.endsWith("To", 10))

It is a case-sensitive method that determines whether the string contains the characters of the specified string or not. It returns true if the string contains characters and returns false if not.

string.includes(searchValue, start)

Let's understand the parameters of this method.

• searchValue: It is a required parameter. It is the substring to search for.
• start: It represents the position where to start the searching in the string. Its default value is 0.

let str = "hello world"

console.log(str.includes('world',5));
console.log(str.includes('World', 11))

It is used to build a new string that contains a specified number of copies of the string on which this method has been called.

string.repeat(count)

This function has a single argument.

• count: It is a required parameter that shows the number of times to repeat the given string. The range of this parameter is from 0 to infinity.

var str = "hello world";
console.log(str.repeat(5));

JavaScript String Methods

Let us see some of the JavaScript methods that are tabulated below: