Need Clarification on JavaScript apply Method

Asked Dec 08 '17 at 04:50

Active Dec 08 '17 at 04:50

Viewed 28 times

Can someone please point out what I am misunderstanding about apply. I have the following code:

function testFunc(input) {
  console.log(Array.isArray(input));
  console.log(input);
}

var obj = {};
var testArr = ["test1", true, 3];

testFunc(testArr);  // first call

testFunc.call(obj, testArr);  // second call

testFunc.apply(obj, testArr);  // third call

As expected, the first and second calls produce the outputs

true and Array["test1", true, 3].

From my understanding of all that I've read on apply, the third call should also produce the same: apply is expecting this (obj) and an array-like argument.

However what I get is

false and test1 (as a string).

How and why is the array being collapsed to its first element? What gives?

Thanks

edited Jun 20 '20 at 09:12

Community

asked Dec 08 '17 at 04:50

Galois Cohomologist

1

https://stackoverflow.com/questions/1986896/what-is-the-difference-between-call-and-apply – epascarello Dec 08 '17 at 04:52
1

because it expects multiple arguments, not an array.... – epascarello Dec 08 '17 at 04:53
`apply` expects an array of arguments as the second argument. Thus `"test1"`, `true`, `3` are passed to `testFunc`. – Andrew Li Dec 08 '17 at 04:54
`function testFunc(input) { console.log(arguments)` – epascarello Dec 08 '17 at 04:54
`apply this with an array of arguments` `call this with arguments` – Jay Harris Dec 08 '17 at 04:55

Need Clarification on JavaScript apply Method

0 Answers0