Question

How to convert part of a string between two indexes to lowercase in JavaScript

Answer 1

function convert_part_to_lowercase(str, start, end) {
    // Extract the part of the string before the start index
    const before = str.substring(0, start);
    
    const upperPart = str.substring(start, end).toLowerCase();
    
    // Extract the part of the string after the end index
    const after = str.substring(end);
    
    return before + upperPart + after;
}
        
    
let s = "JAVASCRIPT PROGRAMMING";
  
s = convert_part_to_lowercase(s, 3, 6);
console.log(s); 
 
s = convert_part_to_lowercase(s, 13, 14);
console.log(s); 



/*
run:
     
JAVascRIPT PROGRAMMING
JAVascRIPT PRoGRAMMING
     
*/

 

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