JS Dart VBScript
types √ √ sort of
getters and setters √ √ √
immutable objects √ √ √
prototypal inheritance √
simulated classes √
"real" classes √ √
closures √ √
weakly bound to JS √ √
obtrusive for JS (global) may be √ √
obtrusive for JS (prototypes) may be √
operator overload √
cross browser √
real benefits for the Web √ ? ?
If you are wondering about JS types, we have both weak type and strong type, e.g. Float32Array.
When StructType and ArrayType will be in place then JS will support any sort of type.
2 comments:
WHAT is the difference between both ?
i think JS is the best script.
Concerning "real" classes: Who's not happy with with prototype inheritance?
It might just be sufficient to add a small thing to ES5 that calls the various implementations of an object's method along its prototype chain, in an efficient manner (built-in).
So, along those lines (sorry for the length of my comment...):
Object.callTopDown = function ( /*object*/o, /*string*/m /*, ... args ...*/ ) {
Object.applyTopDown( o, m, Array.prototype.slice.call( arguments, 2 ) );
}
Object.applyTopDown = function ( /*object*/o, /*string*/m, /*array*/args ) {
// Backtrack the prototype chain of `o` to list all
// implementations of method `m`.
//
// (A built-in version could be much more efficient.)
var arr = []
, prev_impl
, impl
;
for (var o2 = o;
o2;
o2 = Object.getPrototypeOf( o2 ) // ECMAScript 5
)
{
impl = o2[ m ];
if (impl && impl !== prev_impl)
arr.push( prev_impl = impl );
}
if (!arr.length) throw new Error('Method "' + m + '" not found');
// Apply all implementations of method `m`, from the top to the
// bottom of the prototype chain of `o`.
while (impl = arr.pop())
impl.apply( o, args );
}
function test() {
var acc = [];
// Setup a prototype chain
function CA() {}
CA.prototype.doit = function (x,y,z) { acc.push('CA.doit',x,y,z); console.log('CA.doit',x,y,z); };
function CB() {}
CB.prototype = new CA();
// Not overriding here.
function CC() {}
CC.prototype = new CB();
CC.prototype.doit = function (x,y,z) { acc.push('CC.doit',x,y,z); console.log('CC.doit',x,y,z); };
function CD() {}
CD.prototype = new CC();
CD.prototype.doit = function (x,y,z) { acc.push('CD.doit',x,y,z); console.log('CD.doit',x,y,z); };
// Define truth
var expected_acc = [ 'CA.doit', 1, 2, 3, 'CC.doit', 1, 2, 3, 'CD.doit', 1, 2, 3 ];
// Run
d = new CD();
Object.callTopDown( d, 'doit', 1, 2, 3 );
// Check
console.assert( expected_acc.length === acc.length, 'wrong acc.length' );
expected_acc.forEach( checkOne );
function checkOne(x, i) {
console.assert( expected_acc[ i ] === acc[ i ] , 'wrong acc['+i+']:' , acc[i] );
}
}
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