javascript - Refactoring animation code into a class, receiving error on accessing class variable -


a similar different issue recent post of mine -

i'm experiencing error "cannot set property 'globalcompositeoperation' of undefined" when i'm trying access class variable inside prototype call. here code -

var drawslinky = function() {      this.c = document.getelementbyid("c"),      this.w = c.width,      this.h = c.height,      this.ctx = c.getcontext('2d'),            this.prob = .7,      this.minsparks = 3,      this.maxsparks = 10,      this.minarea = 5,      this.maxarea = 40,      this.minvel = 10,      this.maxvel = 50,        this.particles = [],      this.frame = 0;    };    drawslinky.prototype.anim = function(){    this.c.requestanimationframe(this.anim);        this.ctx.globalcompositeoperation = 'source-over';        this.ctx.fillstyle = 'rgba(0, 0, 0, .04)';    this.ctx.shadowblur = 0;    this.ctx.fillrect(0, 0, w, h);        this.ctx.globalcompositeoperation = 'lighter';        ++frame;        if(math.random() < prob) genparticles();        for(var = 0; < particles.length; ++i){      var part = particles[i];      part.use();            if(part.x < 0 || part.x > w ||         part.y < 0 || part.y > h ||         math.random() < .01){        particles.splice(i, 1);        --i;      }    }  };

what's going on?

it should referencing .ctx in drawslinky, i'm getting infinite loop of errors...

update - actually, 2 problems. 1 can't figure out how work without hardcoding this.requestanimationframe(drawslinky.anim); (drawslinky instantiation of drawslinky class),

and two, this.cx.globalcompositeoperation = 'source-over'; isn't referencing ctx drawslinky , putting infinite loop.

so think need both, though second problem made question for

var me = this; this.c.requestanimationframe(function(){   me.anim(); });

the value of set when call function, not when declare it. more info here: https://stackoverflow.com/a/16063711/1641941 under variable

hope helps


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