I remember there is a convention/recommendation to put open开发者_开发问答ing brace in the same line, because of the way JavaScript adds a semicolon or something.
//OK
function blah(){
};
//Probably not OK
function blah()
{
};
But I don't find a relevant source to confirm/deny this.
Is this true? Or just a myth?
The issue you are thinking of is for return
statements.
return {
value: 'test'
}
Works fine, but the following does not:
return
{
value: 'test'
}
JavaScript adds a semicolon after return
turning the above into:
return;
{
value: 'test'
}
This post on Elegant Code gives some explanation of automatic semicolon insertion, but in regard to returning objects, not declaring functions.
Douglas Crockford gives a reason for choosing the K&R style [1]:
"I always use the K&R style, putting the { at the end of a line instead of the front, because it avoids a horrible design blunder in JavaScript's return statement.
The blunder he is referring to is how JavaScript handles the return statement differently in the following two scenarios:
return {
'status': 'ok'
};
... and:
return
{
'status': 'ok'
};
The first one will return an object with a status property, while the latter will return undefined because of semicolon insertion."
[1] Douglas Crockford: JavaScript: The Good Parts: Style (p. 96)
The JavaScript Garden has a chapter about automatic semicolon insertion. It gives good examples when semicolons are added automatically:
JavaScript is not a semicolon-less language, it in fact needs the semicolons in order to understand the source code. Therefore the JavaScript parser automatically inserts them whenever it encounters a parse error due to a missing semicolon.
In your example JavaScript wouldn't encounter an error due to a missing semicolon though.
There is no issue with declaring functions, but you can get into trouble when returning objects:
function foo()
{ // this is OK
return
{ // this is BAD!
name: "bletch"
};
// actually returns undefined!
}
A semi-colon is automatically inserted after the return statement, and that will break your code.
It's a myth. function blah()
is always required to be followed by a expression block, so makes no difference which style you use. The first style is simply the most widely used form.
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