Change an image when input is given

Question

I have a small basic html code with JavaScript . All I want is when I type 3,it should show me an image as specified and for 9 accordingly. This is the demo. Visit http://jsbin.

Answer 1

try something like this

$(function(){

    // you have not given any event
    $('#num').on('keyup', function(){
      var val = this.value;
      if(val.length){//your length checking logically wrong
         var n = this.value.charAt(0);
         if(val && num2img[n]!==undefined){
           $('#cardImage')[0].src = 'data/1357696142_mastercard1'+ num2img[n] +'.gif';
         }else{
           $('#cardImage')[0].src = 'http://placehold.it/100x100/cf5';
         }
      }
    });
})