Convert character to ASCII code in JavaScript

9 thoughts on “Convert character to ASCII code in JavaScript”

1. While the other answers are right, I prefer this way:

   function ascii (a) { return a.charCodeAt(0); }
   

   Then, to use it, simply:

   var lineBreak = ascii("\n");
   

   I am using this for a small shortcut system:

   $(window).keypress(function(event) {
     if (event.ctrlKey && event.which == ascii("s")) {
       savecontent();
       }
     // ...
     });
   

   And you can even use it inside map() or other methods:

   var ints = 'ergtrer'.split('').map(ascii);
   

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2. "\n".charCodeAt(0);
   

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3. If you have only one char and not a string, you can use:

   '\n'.charCodeAt();
   

   omitting the 0…

   It used to be significantly slower than 'n'.charCodeAt(0), but I’ve tested it now and I do not see any difference anymore (executed 10 billions times with and without the 0). Tested for performance only in Chrome and Firefox.

   Reply

4. For those that want to get a sum of all the ASCII codes for a string:

   'Foobar'
     .split('')
     .map(x=>x.charCodeAt(0))
     .reduce((a,b)=>a+b);
   

   Or, ES6:

   [...'Foobar']
     .map(char => char.charCodeAt(0))
     .reduce((current, previous) => previous + current)
   

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5. JavaScript stores strings as UTF-16 (double byte) so if you want to ignore the second byte just strip it out with a bitwise & operator on 0000000011111111 (ie 255):

   'a'.charCodeAt(0) & 255 === 97; // because 'a' = 97 0 
   'b'.charCodeAt(0) & 255 === 98; // because 'b' = 98 0 
   '✓'.charCodeAt(0) & 255 === 19; // because '✓' = 19 39
   

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6. You can enter a character and get Ascii Code Using this Code

   For Example Enter a Character Like A
   You Get Ascii Code 65

   function myFunction(){
       var str=document.getElementById("id1");
       if (str.value=="") {
          str.focus();
          return;
       }
       var a="ASCII Code is == >  ";
   document.getElementById("demo").innerHTML =a+str.value.charCodeAt(0);
   }

   <p>Check ASCII code</p>
   
   <p>
     Enter any character:  
     <input type="text" id="id1" name="text1" maxLength="1">	</br>
   </p>
   
   <button onclick="myFunction()">Get ASCII code</button>
   
   <p id="demo" style="color:red;"></p>

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7. To convert a String to a cumulative number:

   const stringToSum = str => [...str||"A"].reduce((a, x) => a += x.codePointAt(0) - 65, 0);
   
   console.log(stringToSum("A")); // 0
   console.log(stringToSum("Roko")); // 151

   Use case:

   Say you want to generate different background colors depending on a username:

   const stringToSum = str => [...str||"A"].reduce((a, x) => a += x.codePointAt(0), 0);
   
   const UI_userIcon = user => {
     const hue = (stringToSum(user.name) - 65) % 360; // "A" = hue: 0
     console.log(`Hue: ${hue}`);
     return `<div class="UserIcon" style="background:hsl(${hue}, 80%, 60%)" title="${user.name}">
       <span class="UserIcon-letter">${user.name[0].toUpperCase()}</span>
     </div>`;
   };
   
   [
     {name:"A"},
     {name:"Amanda"},
     {name:"amanda"},
     {name:"Anna"},
   ].forEach(user => {
     document.body.insertAdjacentHTML("beforeend", UI_userIcon(user));
   });

   .UserIcon {
     width: 4em;
     height: 4em;
     border-radius: 4em;
     display: inline-flex;
     justify-content: center;
     align-items: center;
   }
   
   .UserIcon-letter {
     font: 700 2em/0 sans-serif;
     color: #fff;
   }

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8. To ensure full Unicode support and reversibility, consider using:

   '\n'.codePointAt(0);
   

   This will ensure that when testing characters over the UTF-16 limit, you will get their true code point value.

   e.g.

   '𐩕'.codePointAt(0); // 68181
   String.fromCodePoint(68181); // '𐩕'
   
   '𐩕'.charCodeAt(0);  // 55298
   String.fromCharCode(55298);  // '�'
   

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9. str.charCodeAt(index)
   

   Using charCodeAt()
   The following example returns 65, the Unicode value for A.

   'ABC'.charCodeAt(0) // returns 65

   Reply