Why does the player jump every time it touches the ground in my JavaScript game?

Question

I am making a javascript game where the player jumps over oncoming cars, but after the first jump every time the player hits the ground they jump again automatically. I believe the problem is because I am resetting the jumping variable to false when it hits the ground yet it is still going through the initial jump() function so it sees it as false and makes it jump again. Is there any way to fix this?

this.isJumping = function(){
  var y=player.y;
  var jumping;

  if (y=area.canvas.height - 200){
    player.image.src="man.png";
  }
  else{
    jumping=true;
    player.image.src="man2.png";
  }
  return jumping;
}

(And later in the code)

function jump() {
  if (!player.isJumping() && area.frameNo>0) {
    player.speedY = -20;
    jumping=true;
  }
}

Answer 1

Update - Nov 28, 2016

One solution to your issue is to switch to mousedown and mouseup with the following event handler, as shared before:

function jumpHandler() {
    if (!player.isJumping() && area.frameNo > 0) {
        player.speedY = -20;
        jumping = true;
    } else {
        jumping = false;
    }
}

Another solution would be to switch over to Phaser input events, which make a bit more contextual sense, but might require some work depending on your implementation.

Phaser also has mouseDown and mouseUp detection which would then be passed to the same handler as before.

All of the above should work, but requires some testing for triage and addressing the issue.

Initial Answer

A quick and easy solution, one that would still depend on your other implementation details, is to have the else block for your jump method set jumping to false.

function jump() {
    if (!player.isJumping() && area.frameNo > 0) {
        player.speedY = -20;
        jumping = true;
    } else {
        jumping = false;
    }
}

Looking at your code makes me think that there may be some scoping issues that would need to be shared to be able to nail down a more accurate and maintainable solution.

Answer 2

You are not setting jumping to false anywhere so it will be true forever, change this:

if (y=area.canvas.height - 200)
{    
    player.image.src="man.png";
}

to this

if (y=area.canvas.height - 200)
{    
    player.image.src="man.png";
    jumping = false;
}

Also, it is not a good idea to use y = area.canvas.height - 200, i would do <= instead, what if the area.canvas.height is odd?