javascript - Changing global Variable from within function -

here im having bit of issue simple script ive written up. aim script reduce given number 1 each time button clicked. cannot appear this.. global variable being number=100 doesnt appear change, or change more once.. apologies not being able explain well. here part im working on..:

<script>   var number = 100;        // number want changed , keep changing each button click   function outcome() {     // button calls function     number = number - 1;   // tries change global number.. :/   }   document.write(number);  // has number written in document </script>  

yes, conceptually right. not calling function, @ least not before writing number document.

btw, number global reference number constructor should use variable name, lowercase @ best.

var num = 100; function outcome() {     num--; } outcome(); document.write(num); // 99 

or

<script> var num = 100; function outcome() {     num--;     alert(num); } </script> <button onclick="outcome()">decrease!</button> 

(demo @ jsfiddle.net)