var foo = {prop:1};
var bar = {prop:2};
var obj = {};
obj[foo] = 'value';
console.log(obj[bar]); //'value'
It is quite confusing why obj[bar] and obj[foo] are same now, whereas foo and bar are not same.
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1Hacketo has provided the correct answer. Also see MDN: Working with objects for more information.Yogi– Yogi2016-01-21 13:53:32 +00:00Commented Jan 21, 2016 at 13:53
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It's also here developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… under "Property names"Wiktor Zychla– Wiktor Zychla2016-01-21 14:42:14 +00:00Commented Jan 21, 2016 at 14:42
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1 Answer
because
obj[foo]='value';
is the same as
obj["[object Object]"]='value';
Object keys are string so it's internally doing foo.toString()
and foo.toString() === bar.toString()
Every objects will return "[object Object]" if used as a key (not talking about arrays, numbers, strings..)
You'll need something that uniquely identify your objects, like below
var foo = {id:"foo", prop:1};
var bar = {id:"bar", prop:2};
var obj = {};
obj[foo.id] = 'value';
console.log(obj[bar.id]); //undefined
3 Comments
Layon Ferreira
Its a implicit behaviour
obj[foo] is doing obj[foo.toString()]
jiten
I will create a new object -
var cc= new Object() then console.log(obj[cc]); //value Conclusion: here object cc will be converted to "[object Object]". here if I will look obj in console- Object {[object Object]: "value"}
Hacketo
@jiten as stated in my answer