This chapter provides knowledge about the new features in ES7.

Exponentiation Operator

ES7 introduces a new mathematical operator called exponentiation operator. This operator is similar to using Math.pow() method. Exponentiation operator is represented by a double asterisk **. The operator can be used only with numeric values. The syntax for using the exponentiation operator is given below −

Syntax

The syntax for the exponentiation operator is mentioned below −

base_value ** exponent_value

Example

The following example calculates the exponent of a number using the Math.pow() method and the exponentiation operator.

<script>
   let base = 2
   let exponent = 3
   console.log(''using Math.pow()'',Math.pow(base,exponent))
   console.log(''using exponentiation operator'',base**exponent)
</script>

The output of the above snippet is as given below −

using Math.pow() 8
using exponentiation operator 8

Array Includes

The Array.includes() method introduced in ES7 helps to check if an element is available in an array. Prior to ES7, the indexof() method of the Array class could be used to verify if a value exists in an array . The indexof() returns the index of the first occurrence of element in the array if the data is found ,else returns -1 if the data doesn”t exist.

The Array.includes() method accepts a parameter, checks if the value passed as parameter exists in the array. This method returns true if the value is found, else returns false if the value doesn”t exist. The syntax for using the Array.includes() method is given below −

Syntax

Array.includes(value)

OR

Array.includes(value,start_index)

The second syntax checks if the value exists from the index specified.

Example

The following example declares an array marks and uses the Array.includes() method to verify if a value is present in the array.

<script>
   let marks = [50,60,70,80]
   //check if 50 is included in array
   if(marks.includes(50)){
      console.log(''found element in array'')
   }else{
      console.log(''could not find element'')
   }

   // check if 50 is found from index 1
   if(marks.includes(50,1)){ //search from index 1
      console.log(''found element in array'')
   }else{
      console.log(''could not find element'')
   }

   //check Not a Number(NaN) in an array
   console.log([NaN].includes(NaN))

   //create an object array
   let user1 = {name:''kannan''},
   user2 = {name:''varun''},
   user3={name:''prijin''}
   let users = [user1,user2]

   //check object is available in array
   console.log(users.includes(user1))
   console.log(users.includes(user3))
</script>

The output of the above code will be as stated below −

found element in array
could not find element
true
true
false