HTML Question
Trying to add 10 to this.y variable, but returns NaN
I seem to have done something wrong and cant find any solutions. I've tried to convert them into numbers and tried += but i get NaN.
function circle() {
this.x = 60;
this.y = 200;
this.draw = function() {
ellipse(this.x, this.y, 20, "green");
};
this.move = function() {
$(document).keydown(function(e) {
// console.log(e.keyCode);
if (e.keyCode === 68) {
this.y += 1;
console.log(this.y);
}
});
};
}
Might it be because they are not variables?
thanks :)
Answer Source
This is because this inside keydown callback is not what your expecting.
One way to solve is to save this of outer scope to variable.
var me = this;
me.x = 60;
me.y = 200;
....
me.y += 1; //use me istead of this.
console.log(me.y);
Other way could be to use es6 lambas, bacause it would bind scope right.
$(document).keydown(e => {//lamba instead of function
if (e.keyCode === 68) {
this.y += 1;
console.log(this.y);
}
});
You can also use bind function to bind scope.
$(document).keydown((function(e) {//lamba instead of function
if (e.keyCode === 68) {
this.y += 1;
console.log(this.y);
}
}).bind(this));