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How to Count the Number of Duplicate Characters in JavaScript?

I need to create a function that returns the number of duplicate characters in a string. It will be case sensitive and spaces are included. If there are no duplicates, return 0.

JavaScript
1 Answer
Mohammad Qandeel
Answered
24 
const duplicates = str => str.length - new Set(str).size;

Example

duplicates('1100') // 2

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