new rule: enforce one of the two Underscore function call forms

[danielmanesku]

What do you think of creating a rule for enforcing one of the two forms of Underscore functions? Should we create a rule for this?

_.min(list, function() {...});
_(list).min(function() {...});

Personally, I prefer the second form.

[HamletDRC]

Sounds good to me. I prefer the 2nd one too.

[loicraux]

Does this apply to all Underscore methods ? Or should it apply to only a subset of the methods (like the ones for collections (http://underscorejs.org/#collections) ?

[danielmanesku]

I would say collections and arrays (at least)

[loicraux]

Not sure if we can enable this rule... :

I just discovered that this code does not build :

function foo(dic: _.Dictionary<number>) : void {
    _(dic).forEach((val: number, key: string): void => {});
}

Error is :

error TS2345: Argument of type '(val: number, key: string) => void' is not assignable to
parameter of type 'ObjectIterator<Dictionary<number>, void>'.
  Types of parameters 'val' and 'element' are incompatible.
    Type 'number' is not assignable to type 'Dictionary<number>'.
      Index signature is missing in type 'Number'.

Whereas this one does build :

function foo(dic: _.Dictionary<number>) : void {
    _.forEach(dic, (val: number, key: string): void => {});
}

I don't know if this is an error in underscore.d.ts ... I have to check.

[danielmanesku]

Might be a bug in our d.ts. file.

This works:

_.forEach([1, 2, 3], function(num) { console.log(num); })
_([5, 6, 7]).forEach(function(num) { console.log(num); })

Test it here: https://jsfiddle.net/kms3y8b8/. Enable developer tools to see the output and click on Run.