how is any of this less-confusing than a simple style-guide of pre-declaring
all variables @ the beginning of a function?
again, there’s zero legitimate reason why javascript even needs block-level
scoping of variables (and arguing because other languages have it is not a
reason). you're just creating more needless javascript style-guide variance
that further confuses your team-members / project-successor.
```
/*jslint
bitwise: true,
browser: true,
maxerr: 8,
maxlen: 100,
node: true,
nomen: true,
regexp: true,
stupid: true
*/
(function () {
'use strict';
// es5 best-practice of declaring all variables at beginning of function,
// and runtime-checked by 'use strict' pragma
var bar,
c0,
c1,
foo,
getTeamArray,
people,
v1,
xx,
yy;
getTeamArray = function () {
return [1, 2, 3];
};
people = getTeamArray();
if (people.length > 2) {
console.log("it's a crowd", people.join(','));
} else if (people.length === 2) {
console.log("just a pair");
} else if (people.length === 1) {
console.log("solo");
} else {
console.log("none");
}
// output: it's a crowd 1,2,3
bar = function () {
return 0;
};
foo = function () {
return 50;
};
(function () {
xx = foo();
if (xx < 50) {
console.log(xx); // yy is not available here
return;
}
yy = bar();
if (yy > 0) {
console.log(yy);
return;
}
// else
console.log(xx, yy);
}());
// output: 50 0
c0 = null;
c1 = function (xx) {
return xx;
};
v1 = false;
// 'unset' xx
xx = undefined;
(function () {
if (c0) {
console.log(c0); // xx is not available here
return;
}
xx = v1;
if (c1(xx)) {
console.log(xx);
return;
}
// else
console.log(c0, xx);
}());
// output: null false
}());
```
> On Mar 22, 2018, at 1:56 AM, Mike Samuel <[email protected]> wrote:
>
>
>
> On Wed, Mar 21, 2018 at 11:02 AM, Rodrigo <[email protected]
> <mailto:[email protected]>> wrote:
> My proposal is to keep it simple and implement the if-assignment `if(
> const o = ...; ! o ) { ... }` mimicking the `for(;;)` assignment
> behavior.
>
> Fair enough. If the assignment is separate from the condition, then none of
> that matters.
> That question only pertained to let/const declarations used for their value.
>
> That way we can scope a variable to the `if` block and we can do that
> *separately* from assignment.
>
> Assigning and comparing at the same time opens up all sort of oddities
> as the variable transitions from lvalue to comparison operand. This
> already exists in the language and is definitely not good practice.
>
> `if.value`, as proposed earlier is a bombshell similar to `this`,
> which could easily get scrambled with the introduction of additional
> `if` blocks.
>
> The beauty of `if(;)` is that it makes scope blocks possible while
> avoiding the asymmetric behavior caused by assigning and comparing in
> one go.
>
> if( let people=getTeamArray(); people.length > 2 ) {
> console.log("it's a crowd", people.join(','));
> }
> else if( people.length == 2 ) {
> console.log("just a pair");
> }
> else if( people.length == 1 {
> console.log("solo");
> }
> else {
> console.log("none");
> }
>
> IIUC, it sounds like the right side could be syntactic sugar for the left
> side.
> If that's right, what about the left side warrants new syntax to enable the
> right?
>
>
> Current Proposed
> {
> let people = getTeamArray();
> if( people.length > 2 ) {
> console.log("it's a crowd", people.join(','));
> }
> else if( people.length == 2 ) {
> console.log("just a pair");
> }
> else if( people.length == 1 {
> console.log("solo");
> }
> else {
> console.log("none");
> }
> }
> if( let people = getTeamArray(); people.length > 2 ) {
> console.log("it's a crowd", people.join(','));
> }
> else if( people.length == 2 ) {
> console.log("just a pair");
> }
> else if( people.length == 1 {
> console.log("solo");
> }
> else {
> console.log("none");
> }
>
> I can imagine that it might be nice when used later in an else-if chain:
>
> if (c0) {
> ...
> } else (let x = v1, c1(x)) {
> ...
> } else ...
>
> vs
>
> if (c0) {
> ...
> } else {
> let x = v1;
> if (c1(x)) {
> ...
> } else ...
> }
>
> Can you point at any particularly tricky code that could be simplified by
> this?
> _______________________________________________
> es-discuss mailing list
> [email protected] <mailto:[email protected]>
> https://mail.mozilla.org/listinfo/es-discuss
> <https://mail.mozilla.org/listinfo/es-discuss>
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
