Why is it taking my function and making it not a function anymore?

I have a function that returns a random number from 1-10. When I use it in my other function it works once, but then it starts having an error that it's not a function. This isn't the exact code, just an example code that's similar. It produces an error saying "TypeError: Property 'ran' of object [object DOMWindow] is not a 开发者_高级运维function" Why is it doing this?

Thanks alot

var buffer = [];

function ran() { 
   return Math.round(Math.random()*10);
};

function test(){
   var size = 6;
   for (i=0; i<=size;i++) {
      var num = ran();
      if (num === 2 || num === 3){
         buffer.push(num);
      };
   };
};

Your code is fine, but from the error it looks like you're assigning some value to an implied global variable called ran somewhere else in your code.

var buffer = [];

function ran() { 
   return Math.round(Math.random()*10);
};

function test() {
   var size = 6;
   for (i=0; i<=size;i++) {
      var num = ran();
      if (num === 2 || num === 3){
         buffer.push(num);
      };
   };
};

// ... somewhere else:

function someOtherFunction() {
   ran = 5;  // This will break your run() function when 
             // someOtherFunction() is called.
}

If this is the case, make sure to limit the scope of your variables to the function in which they are declared by using the var keyword:

// ... somewhere else:

function someOtherFunction() {
   var ran = 5;  // This will limit the scope of ran and will 
                 // not conflict with the run() function.
}