
I think this is the way it is typically used here and elsewhere. reserving "brackets" without a qualifier for indicating square brackets., so probably no explanation is necessary. But, for those who want to know more: It does seem to be the case that in British English "brackets" typically means "round brackets", which are parentheses, but in American English "brackets" typically means square brackets ("[]"). Admittedly, "brackets" is easier to spell. And to pronounce. Even to type, once you get used to it.
1.1 KiB
Error!
Try it:
let user = {
name: "John",
go: function() { alert(this.name) }
}
(user.go)() // error!
The error message in most browsers does not give us much of a clue about what went wrong.
The error appears because a semicolon is missing after user = {...}
.
JavaScript does not auto-insert a semicolon before a bracket (user.go)()
, so it reads the code like:
let user = { go:... }(user.go)()
Then we can also see that such a joint expression is syntactically a call of the object { go: ... }
as a function with the argument (user.go)
. And that also happens on the same line with let user
, so the user
object has not yet even been defined, hence the error.
If we insert the semicolon, all is fine:
let user = {
name: "John",
go: function() { alert(this.name) }
}*!*;*/!*
(user.go)() // John
Please note that parentheses around (user.go)
do nothing here. Usually they setup the order of operations, but here the dot .
works first anyway, so there's no effect. Only the semicolon thing matters.