javascript - how should I bind this through a function? -

javascript - how should I bind this through a function? -

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how access right `this` / context within callback? 4 answers

i've code below:

function foo(){ $('div').each(function(){ //here $(this) refers selected div }); });

now, when phone call foo in setinterval $(this) won't referring div of each() method:

setinterval(function(){ foo(); },5000);

i tried bind():

setinterval(function(){ foo(); }.bind(this),5000); //or bind(document.queryselectorall('div'))

i'm incorrectly referring div $(this) really. should do?

here's proof i'm getting undefined:

assuming want code within each callback have access whatever value this has when setinterval phone call made, code has 2 problems.

the first you're not binding foo itself. code

setinterval(function(){ foo(); }.bind(this),5000);

successfully binds this anonymous function function() { foo(); }. anonymous function makes direct phone call foo, (in non-strict mode) sets this phone call global object window or global, happens direct function call.

you need explicitly pass on anonymous function's this foo phone call within anonymous function call or apply:

setinterval(function(){ foo.call(this); }.bind(this),5000);

now foo has right this, need create this value accessible within of each callback. that, can consult how access right `this` / context within callback?, instruct store outer this in variable. store this within variable , utilize variable instead of this within inner callback:

function foo() { var outer_this_from_foo = this; $('.rscontent').each(function(){ //here $(this) refers selected div //but outer_this_from_foo refers `this` value outside callback var fi = $('>.img-responsive', outer_this_from_foo); // instead of $('>.img-responsive', this) }); };

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