Question

How to convert a character inside string to lowercase in JavaScript

Answer 1

String.prototype.replaceAt = function(i, replacement_ch_s) {
    return this.substr(0, i) + replacement_ch_s + this.substr(i + replacement_ch_s.length);
}
  
function char_to_lowercase(s, idx) { 
    let len = s.length;
     
    if (idx < 0 || idx > len) return s;
    
    for (let i = 0; i < len; i++) { 
         if (i === idx && s[i] >= 'A' && s[i] <= 'Z') {
             s = s.replaceAt(i, s.charAt(i).toLowerCase());
         }
    } 
      
    return s;
} 
        
    
let s = "JAVASCRIPT PROGRAMMING";
  
s = char_to_lowercase(s, 0);
console.log(s);
  
s = char_to_lowercase(s, 4);
console.log(s); 
 
s = char_to_lowercase(s, s.length - 1);
console.log(s);   
 
 
    
    
/*
run:
     
jAVASCRIPT PROGRAMMING
jAVAsCRIPT PROGRAMMING
jAVAsCRIPT PROGRAMMINg
     
*/
 

 

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Answer 2

function char_to_lowercase(str, charToConvert) { 
    let index = str.indexOf(charToConvert);

    if (index !== -1) {
        let convertedChar = str.charAt(index).toLowerCase();
        str = str.substring(0, index) + convertedChar + str.substring(index + 1);
    }
      
    return str;
} 
        
    
let str = "JAVASCRIPT PROGRAMMING";
  
str = char_to_lowercase(str, 'T');
console.log(str); 

str = char_to_lowercase(str, 'A');
console.log(str); 

    
    
/*
run:
     
JAVASCRIPt PROGRAMMING
JaVASCRIPt PROGRAMMING
     
*/
 

 

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