javascript - Access this from callback inside member function -

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• how access correct `this` inside callback? 5 answers

i'm trying access class instance callback within member function. 1 example how like:

myclass.prototype.foo = function(){     var arr = [1, 2, 3];     arr.foreach(function(element){         //the next line doesn't work         //becuase doesn't reference myclass-instance anymore         this.elements.push(element);     }); } 

here of course work loop (for(var = 0; < arr.length; i++) {...}) there situations can't.

i found 1 way access myclass instance:

myclass.prototype.foo = function(){     var arr = [1, 2, 3];     var mycurrentinstance = this;    //store temporary reference     arr.foreach(function(element){         //here works because use temporary reference         mycurrentinstance.elements.push(element);     }); } 

this doesn't seem clean me. there better way?

foreach has optional thisarg can pass after passing callback, should work:

myclass.prototype.foo = function(){     var arr = [1, 2, 3];     var mycurrentinstance = this;    //store temporary reference     arr.foreach(function(element){         //here works because use temporary reference         this.elements.push(element);     }, this); } 

heres function definition:

arr.foreach(callback[, thisarg]) 

heres documentation: https://developer.mozilla.org/en-us/docs/web/javascript/reference/global_objects/array/foreach

update

you can use bind pass argument, though doesn;t prettier imho:

myclass.prototype.foo = function(){     var arr = [1, 2, 3];     var mycurrentinstance = this;    //store temporary reference     var myfunc = function(element){         //here works because use temporary reference         this.elements.push(element);     }.bind(this);     myfunc(); } 

(i know bad example, demonstrates binding does)