Why does my javascript not work when I use an if statement in my function -

so i'm javascript beginner , i'm working on making calculator. right i'm testing out addition button i'm having troubles code on equal button. code button :

  function equalpress() {    storednumbertwo = document.getelementbyid("output").innerhtml;   // if(sign === 1) {   calc = +storednumbertwo + +storednumber;   document.getelementbyid("output").innerhtml = calc;   // }   } 

i've commented out if statement show i've done sort of working. when don't use if statement can equals sign add , work properly, however, not going work when i'm adding in other operators. sign variable going use switch operator pressed 1= +, 2 = -, etc... anyways when add if statement in can test see operator pressed whole calculator freezes , can't press buttons. i'm not sure why happening, i've tried using switch instead of if statements , i've used various types of variables condition , hasn't worked. appreciated. here fiddle. https://jsfiddle.net/rk1mu4rb/3/

don't use var access variables declared in outer scope. var keyword inside function creates new variable local function, hiding other variables same name defined outside.

i've updated fiddle , removed var part sign = 1: https://jsfiddle.net/rk1mu4rb/4/