Javascript function stored in variable error

Question

Is there any reason why I would be getting the error

Uncaught TypeError: inter is not a function at movingPiece (script.js:270) at keyboardMove (script.js:146)

in this code:

var inter = setInterval(function() {
  draw();
  b_ctx.globalCompositeOperation = "copy";
  b_ctx.fillStyle = "purple";
  b_ctx.beginPath();
  b_ctx.arc(xcoord, y, 45, 0, Math.PI * 2, true);
  b_ctx.fill();
  y += 1;
  if (y > endY) clearInterval(inter)
}, 25);

inter();

setInterval does not return a function?! Just drop the inter(); statement and your code should work. Why did you think did you need it, what did you expect it to do? — Bergi
– Bergi, Commented May 14, 2017 at 10:59
It is basically an animation where a circle drops vertically. I wasn't sure if I needed to call inter() at the end — jimbo123
– jimbo123, Commented May 14, 2017 at 11:06

user8003769 · Accepted Answer · 2017-05-14 11:00:55Z

1

inter is not really a function. So you can't call it. It is called automatically every 25 millisecond.

You are getting the error because you are calling it. It is automatically called. You don't need to call it or invoke it.

answered May 14, 2017 at 11:00

user8003769

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Comments

mrinalmech · Accepted Answer · 2017-05-14 11:02:41Z

0

setInterval does not return a function. Modify it like this.

   var inter = function(){
                    var interVar = setInterval(function(){
                    draw();
                    b_ctx.globalCompositeOperation="copy";
                    b_ctx.fillStyle = "purple";
                    b_ctx.beginPath();
                    b_ctx.arc(xcoord, y, 45, 0, Math.PI*2, true);
                    b_ctx.fill();
                    y+=1;
                    if(y>endY) clearInterval(interVar)}, 25);
               }

Then you can run inter() and have it run setInterval

answered May 14, 2017 at 11:02

mrinalmech

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3 Comments

jimbo123 Over a year ago

Hi I've been using this code but for some reason, the y variable doesn't increment. I've set the variable to y=55 before your code and it just stays at 55

jimbo123 Over a year ago

The console doesn't print any errors either. I put an alert("boom") before the if statement and it doesn't execute. It just carries on to the end and goes back to the calling function

mrinalmech Over a year ago

Pass the y variable as a function parameter and call inter(y)? Might be a scoping issue.

warch · Accepted Answer · 2017-05-14 11:06:52Z

0

Try this:

var inter = function(){
  var x= setInterval(function(){
                draw();
                b_ctx.globalCompositeOperation="copy";
                b_ctx.fillStyle = "purple";
                b_ctx.beginPath();
                b_ctx.arc(xcoord, y, 45, 0, Math.PI*2, true);
                b_ctx.fill();
                y+=1;
                if(y>endY) clearInterval(x)}, 25);
}
inter();

edited May 14, 2017 at 11:06

answered May 14, 2017 at 11:04

warch

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1 Comment

mrinalmech Over a year ago

That will throw an error as you cannot run clearInterval on inter which is the container function now.

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