Question

How to convert a string lowercase characters to uppercase and uppercase to lowercase with 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 flip_characters(s) { 
    var len = s.length;
  
    for (var i = 0; i < len; i++) { 
         if (s[i] >= 'A' && s[i] <= 'Z') {
             s = s.replaceAt(i, s.charAt(i).toLowerCase());
         }
         else {
             if (s[i] >= 'a' && s[i] <= 'z') 
                 s = s.replaceAt(i, s.charAt(i).toUpperCase());
         }
    } 
    
    return s;
} 
      
  
var s = "jaVAscRiPt prOGrAmminG";

s = flip_characters(s);
        
document.write(s);

   
  
  
/*
run:
   
JAvaSCrIpT PRogRaMMINg 
   
*/

 

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