What is set.has() method in TypeScript?

Overview

In TypeScript, we can use the has() method of a set to check if the set contains the specified entry. Sets are used to store unique values that have no duplicates.

Syntax

set.has(value)
Syntax for the has() method of a Set in Typescript

Parameters

  • set: This is the set we want to check if it contains the specified value.
  • value: This is the value that we want to check if it exists.

Return value

If the set contains the specified value, then a true is returned. Otherwise, false is returned.

Code example

Let's look at the code below:

// create some sets
let names = new Set<string>(["Theodore", "David", "John", "Janme"])
let evenNumbers = new Set<number>([2, 4, 6, 8, 10, 12])
let booleanValues = new Set<boolean>([true, false])
let countries = new Set<string>(["Nigeria", "Brazil", "Ghana", "Egypt", "Germany"])
// check if they contain some values
console.log(names.has("Theodore"))    // true
console.log(evenNumbers.has(5))       // false
console.log(booleanValues.has(true))  // true
console.log(countries.has("Tokyo"))   // false

Code explanation

  • Lines 2 to 5: We create some sets in TypeScript.
  • Lines 9 to 12: We use the has() method to check if some entries are contained in the sets we created. Then we print the results to the console.

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