Question

How to determines whether a character is a letter or a digit in JavaScript

Answer 1

var ch = '9';
if (isLetter(ch) || isDigit(ch))
    document.write("yes<br />");
else
    document.write("no<br />");
     
var ch = 'a';
if (isLetter(ch) || isDigit(ch))
    document.write("yes<br />");
else
    document.write("no<br />");
    
var ch = '@';
if (isLetter(ch) || isDigit(ch))
    document.write("yes<br />");
else
    document.write("no<br />");
 
 
function isLetter(ch){
    return ch.length === 1 && ch.match(/[a-z]/i);
}
function isDigit(ch){
    return !isNaN(ch)
}
 
/*
run:
   
yes
yes
no
     
*/

 

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