How to use a Map In Javascript
Using a Map, iterate through the string, storing each character as a key and its count as the value. If a character is already in the map, return true; otherwise, continue. If no characters repeat, return false.
Example: In this example we counts duplicate characters in a string using a Map, then prints them or a message if none exist.
const inputStr = "w3wiki";
const charCount = new Map();
// Count occurrences of each character
for (const char of inputStr) {
if (charCount.has(char)) {
charCount.set(char, charCount.get(char) + 1);
} else {
charCount.set(char, 1);
}
}
const duplicates = [];
// Find characters with count > 1
for (const [char, count] of charCount) {
if (count > 1) {
duplicates.push(char);
}
}
// Print duplicates or no duplicates message
if (duplicates.length > 0) {
console.log(`The duplicate characters: ${duplicates.join(', ')}`);
} else {
console.log(`The string "${inputStr}" has no duplicate characters.`);
}
Output
The duplicate characters: G, e, k, s
JavaScript Program to Check for Repeated Characters in a String
In this article, we are going to see various methods with which you can detect repeated characters in a string. Checking for repeated characters in a string involves examining the string’s content to identify if any character occurs more than once. This helps detect duplications or repetitions within the text.
Input: Str = “w3wiki”
Output:
e, count = 4
g, count = 2
k, count = 2
s, count = 2
Explanation: e,g,k,and s are characters which are occured in string in more than one times.
There are several methods that can be used to Check for repeated characters in a string JavaScript.
Table of Content
- Using sort() method with for…of loop
- Using a Set in JavaScript
- Without using Extra Data Structure
- Using a Map
- Using Object as a Frequency Counter:
We will explore all the above methods along with their basic implementation with the help of examples.
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