I did this by accident...

var numbers = [1, 2, 3, 4];
numbers.push[5];

Why wasn't there an error message?

push needs parentheses, not square brackets. It was just a simple typo. I wasn't paying close enough attention to what I was doing... but why wasn't there an error message?

As far as I can tell, the numbers array wasn't modified in any way. It just did... nothing.

I did this by accident...

var numbers = [1, 2, 3, 4];
numbers.push[5];

Why wasn't there an error message?

push needs parentheses, not square brackets. It was just a simple typo. I wasn't paying close enough attention to what I was doing... but why wasn't there an error message?

As far as I can tell, the numbers array wasn't modified in any way. It just did... nothing.

• javascript
• arrays

Share Follow asked Jan 14, 2018 at 23:18 VinceVince 4,23233 gold badges3737 silver badges5959 bronze badges 2

• 1 because that simply evaluates to undefined - any property (functions are just properties in javascript anyway) can have properties ... – Jaromanda X Commented Jan 14, 2018 at 23:20
• 3 Because it is just accessing the property named 5 on the property named push. There isn't a syntax error there, just a logic one – Patrick Evans Commented Jan 14, 2018 at 23:21

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1 Answer 1

Sorted by: Reset to default 9

numbers.push is simply a function but you are attempting to find the property located at key 5 from it, which will evaluate to undefined.

function test() {
  console.log("test");
}


// test[5] evaluates to `undefined` and does nothing
console.log(test[5]);

// We can even manually set this without messing up the function
test[5] = "foo";

// outputs "foo"
console.log(test[5]);

// outputs our expected value "test"
test();