JavaScript string.includes() Method

1. Syntax of string.includes() :
2. Example Codes: Use string.includes() Method to Find a String with Required Parameter targetString
3. Example Codes: Use string.includes() Method to Find a String with Optional Parameter indexPosition
4. Example Codes: Use string.includes() Method to Find a String with Case Sensitivity
5. Example Codes: Use string.includes() Method to Find a String in Real-World Scenario

In Programming languages, Strings are considered a series of characters. JavaScript string is not out from that, but the interesting thing JavaScript does is automatically convert strings to a String Object. As a result, we can easily access the methods and properties of a String with a (.) notation. The string.includes() method is one of them.

Syntax of string.includes() :

string.includes(targetString, indexPosition)

Parameters

Return

A Boolean value from the string Returns true if the string exists; otherwise, false.

Important: the string.includes() Method is case-sensitive. That means it will not match if the actual string is in upperCase form and you search for lowerCase from.

Example Codes: Use string.includes() Method to Find a String with Required Parameter targetString

let str = 'Good things come to those who wait'

console.log(str.includes('come'))
console.log(str.includes('go'))

Output:

true
false

We provide a string come to check whether it exists in the str or not. In that case, the str.includes() method finds the string and returns true

We provide another sting go which does not exist in the str and returns false

Example Codes: Use string.includes() Method to Find a String with Optional Parameter indexPosition

let str = 'Look before you leap'

console.log(str.includes('before', 5))
console.log(str.includes('before', 10))

Output:

true
false

We provide a string before with an index position 5. The str.includes() method to start searching the targeted string from the index position 5. The given string before starts from the index position 5 and returns true.

We also check the same string, but we provide the index position 10 this time. As a result, the method cannot find the string and returns false.

Example Codes: Use string.includes() Method to Find a String with Case Sensitivity

let str = 'FACE THE MUSIC'

console.log(str.includes('FACE'))
console.log(str.includes('face'))

Output:

true
false

We provide a string FACE in the upper case form and the str.includes() method finds the string at the exact form and returns true.

We provide the same string face but this time in the lower case form. Even the letters are the same, but it does not match the form with the actual string, and the str.includes() method returns false.

Example Codes: Use string.includes() Method to Find a String in Real-World Scenario

let fruitStore = ['Apple', 'Orange', 'Mango', 'Cherry', 'Graps']

console.log(fruitStore.includes('Orange'))
console.log(fruitStore.includes('Banana'))

Output:

true
false

Suppose we have an e-commerce application where we sell different fruits. We have an array of strings on our program that stores all the fruit’s names. Now, we want to check if a specific fruit is available in the store or not. To do so, we have used the str.includes() method.

We provide a string Orange to check whether it exists on the fruitStroe or not. The includes() method finds the fruit and returns true.

We provide another string, Banana, to the includes() method. This time it does not find any fruit names Banana and returns false.