On Mon, Dec 3, 2012 at 5:21 PM, Andrea Giammarchi < [email protected]> wrote:
> IMHO, a set(key, value) should return the value as it is when you address > a value > > var o = m.get(k) || m.set(k, v); // o === v > > // equivalent of > > var o = m[k] || (m[k] = v); // o === v > > a set with a key that returns `this` is a non case so almost as useless as > the void return is. > > Usefulness comes with use cases ... except this jQuery chainability thingy > that works fine for jQuery structure ( an ArrayLike Collection ) > A collection is a collection. who asked for map.set(k0, v0).set(k1, v1).set(k2, v2) ? Or even > map.set(k0,v0).get(k1) ? what are use cases for this? > > I am honestly curious about them because I cannot think a single one ... > specially with the Set > > s.add(k0).add(k1).add(k2) ... this code looks weird inlined like this ... > You're completely ignoring the iterator APIs and forEach—either of which a program might want to call on an object post-mutation: Add value to the Set and... - get a fresh iterable for the values (or keys, or entries): set.add( value ).values(); - send each value in the set to another operation: set.add( value ).forEach( item => ...send to some operation.... ); - spread into an array of unique items: [ ...set.add(value) ]; // always unique! yay! Add a key and value to the Map and... - get a fresh iterable for the keys (or values, or entries) map.set( key, val ).keys(); map.set( key, val ).values(); map.set( key, val ).entries(); - send each to pair to another operation (see above) - spread into an array of pairs (see above) Being able to express the complete operation and get mutated object back at once is a compelling use case. Rick >
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