How does this Javascript one-liner function work?

Question

var hasAll = Object.keys(obj1).every(Object.prototype.hasOwnProperty.bind(obj2));

@vahdet this implementation i understood var hasAll = Object.keys(obj1).every(key => obj2.hasOwnProperty(key )); But the one mentioned in question how its similar to this one? — avisek, Feb 27 '19 at 08:40

score 1 · Accepted Answer · edited Feb 28 '19 at 04:29

1

It borrows Object#hasOwnProperty from the prototype of Object and uses bj2 as this object with binding (Function#bind).

The result is a function, which can be used as callback.

edited Feb 28 '19 at 04:29

Emma

answered Feb 27 '19 at 08:25

Nina Scholz

Is it similar to this implementation var hasAll = Object.keys(obj1).every(key => obj2.hasOwnProperty.bind(key )); – avisek Feb 27 '19 at 08:34
no, because you bind the key and get a function with no use. `bind` returns a fucntion which is always truthy. so no real check is happening. – Nina Scholz Feb 27 '19 at 08:39
oh my bad! what if i remove the bind. then? – avisek Feb 27 '19 at 08:41
then it should work, because you have an object `obj2` and a function for checking. – Nina Scholz Feb 27 '19 at 08:43

1 Answers1