TypeScript map function to change property type

Question

I am trying to use map function to transform property type.

class A {... }
class B {... }

var var1 = [{path:"aa",comp:"A"},{path:"b",comp:"B"}];
var var2 = var1.map(function(obj){ 
   var rObj = {path: obj.path, component: A};
   return rObj;
});

The above code will return to var2

[{path:"aa",comp:A},{path:"b",comp:A}]

What I need is

[{path:"aa",comp:A},{path:"b",comp:B}]

How can I achieve this purpose?

Nitzan Tomer · Accepted Answer · 2016-05-14 19:21:51Z

3

You're trying to map between a class name (as string) to the actual class.
You can just maintain a mapping object like so:

class A { ... }
class B { ... }

var nameToClassMapping = {
    A: A,
    B: B
};

var var1 = [{ path: "aa", comp: "A" }, { path: "b", comp: "B" }];
var var2 = var1.map(function(obj) { 
    var rObj = { path: obj.path, component: nameToClassMapping[obj.comp] };
    return rObj;
});

Code in playground

edited May 14, 2016 at 19:21

answered May 14, 2016 at 14:30

Nitzan Tomer

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4 Comments

Nitzan Tomer Over a year ago

I ran the code and it returned the expected result. Check the link to playground in my answer (just added it)

Shawn Over a year ago

If class A and B is define in the same file it works as expected. But if the class is an imported one using import {A,B} from ... then the component property showed undefined. Why is so?

Nitzan Tomer Over a year ago

are you sure that the classes were loaded? if you do console.log(A, B) after the import what do you get?

Shawn Over a year ago

My bad. I mismatched property name and type in nameToClassMapping . Thanks you so much for your patience with me. It works great.

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