Discussion on: ES6 Mini Crash Course: How to Write Modern JavaScript

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Mehdi Raash • Sep 4 '19 • Edited

[...someVariable] it's actually spread attribute not operator.

Jan 13 '17

538

... are called spread attributes which, as the name represents, it allows an expression to be expanded.

var parts = ['two', 'three']
var numbers = ['one', ...parts, 'four', 'five']; // ["one", "two", "three", "four", "five"]

And in this case (I'm going to simplify it).

// Just assume we have an

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Thanks for the recap

Oli Lalonde • Sep 11 '19

The term "spread attribute" is mostly used by React/JSX. Not that it really matters, but the most correct terminology would probably just be "spread syntax" (the ECMAScript spec only refers to it as "SpreadElement" in its grammar).

Chris Achard • Sep 4 '19

Interesting... heh - so, on that page it's called all four of these things:

Spread attribute
Spread operator
Spread syntax
Spread notation

... and it seems to all refer to the same thing :)

I've also found "official" docs calling it at least three of those things 🤣

Is there an actual "official, for real" source for what it's called?

Mehdi Raash • Sep 4 '19

I believe, operators need operand(s).

ECMA divided this topic to:

Arithmetic Operators
Comparison Operators
Logical Operators
Assignment Operators
Conditional Operators

Chris Achard • Sep 4 '19

Hm, interesting. Does the variable that the three dots are on not count as an operand? (I don't know what the formal definition is)

Mehdi Raash • Sep 4 '19

Somehow yes, but I think because this '...' thing introduced the time that syntactic sugar came up to JS so they tend to keep it as just helper syntax, some developers don't like it to be called as an operator because of other programming languages same debate.(some folks in this way would say one language has got more operators to another...:-))

Chris Achard • Sep 4 '19

Got, it (I think :) ). Interesting! I wasn't aware of the debate over the "operator" word. Thanks :)