CODEWITHSUNDEEP
javascriptarchitectureframeworksconstructorprototypal-inheritance
Max
Max

Reputation: 1501

Javascript constructor, prototype and instantiation. Architecture and Framework

I'm developing a "framework" and find myself at writing modules.

for each module exists a set of common initialization rules and common set of functions.

STEP 1. constructor function:

var ns = "namespace1";
t.scenarios[ns] = function (container, instanceName, options) {
    // common for all scenarios, e.g. options initialization
    t.core.defaultScenarioConstructor(this, ns, container, instanceName, options)

    // things only for NAMESPACE1
    this.PROPERTY1 = 1;
}

STEP 2. (question related) then I have a prototype

var p = t.scenarios[ns].prototype;

p.newfunction = function(){
    this.PROPERTY1; // accessible
}

which gets filled with THINGS_ONLY_FOR_NAMESPACE1

t.core.defaultScenarioPrototype(p);

STEP 3 / 4. instantiate class (with new keyword) & call dom builder

p.initNewView = function(container) {/* build dom and assign handlers*/}


Now the question... I would like to do common constructor/prototype initialization within the other "core" module. If on STEP 2 we add functions to prototype then they have "this" keyword and can access CURRENT_INTANCE fields, e.g. PROPERTY1.

If however the prototype is passed as a variable to "defaultScenarioPrototype" builder, then all functions have the other "this" of CORE class, where lives the builder.
How should we add "common" functions to a prototype from another module?

Upvotes: 0

Views: 88

Answers (1)

HMR
HMR

Reputation: 39260

As requested I'll add my comment as an answer. To call a function within a certain this context you can use Function.prototype.call, Function.prototype.apply or Function.prototype.bind.

Bind is used a lot in cases where you pass a callback and don't want to use closures:

setTimeout(myOjbect.somefunction,100);//this in somefunction is window

setTimeout(function(){
  myObject.somefunction();
},100);//this in somefunction is myObject but a closure is created

setTimeout(myObject.somefunction.bind(myObject),100);//this is myObject 
                                    //and no closure is created

One would assume that bind uses less memory and is faster but I recently read somewhere that bind is actually slower than passing a closure so I'm not sure about the memory consumption either.

Upvotes: 1

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