如何从已知子对象ID的对象中检索子对象

Question

I have an object called Suppliers where the id is always unique as follows:

var suppliers = {
    Supplier1: {
        id: 1,
        name: 'Supplier1',
        SVGTemplate: 'svg-supplier1'
    },
    Supplier2: {
        id: 2,
        name: 'Supplier2',
        SVGTemplate: 'svg-supplier2'
    },
    Supplier3: {
        id: 3,
        name: 'Supplier3',
        SVGTemplate: 'svg-supplier3'
   }
}

How can I return the sub-object (eg return suppliers.Supplier1) when all I know is the id of the sub object? I tried to use .filter, but that only seems to work on arrays:

function findById(source, id) {
    return source.filter(function (obj) {
        return +obj.id === +id;
    })[0];
}

var supplierarray = findById(suppliers, myKnownID);
return supplierarray;

Answer 1

You need to loop over the object using for-in loop, you tried to use .filter which is for array.

So you can change findById definition to below

var suppliers = {
    Supplier1: {
        id: 1,
        name: 'Supplier1',
        SVGTemplate: 'svg-supplier1'
    },
    Supplier2: {
        id: 2,
        name: 'Supplier2',
        SVGTemplate: 'svg-supplier2'
    },
    Supplier3: {
        id: 3,
        name: 'Supplier3',
        SVGTemplate: 'svg-supplier3'
   }
}
// Should return single object not array, as id is unique as OP said 
function findById(source, id) {
   for(var key in source){
     if(source[key].id === id){
       return source[key];
     }
   }
  return null;
}

findById(suppliers,3);// {id: 3, name: "Supplier3", SVGTemplate: "svg-supplier3"}

Answer 2

Object.keys(suppliers).map(key => suppliers[key]).find(({id}) => id === someId);

Answer 3

You can search for any key in its child objects.

 Object.prototype.findBy = function(propName, propVal){

    for( var i in this ){

         if( this[i][ propName ] == propVal ){
            return this[i];
        }
    }
    return undefined;
};

var suppliers = {
    Supplier1: {
        id: 1,
        name: 'Supplier1',
        SVGTemplate: 'svg-supplier1'
    },
    Supplier2: {
        id: 2,
        name: 'Supplier2',
        SVGTemplate: 'svg-supplier2'
    },
    Supplier3: {
        id: 3,
        name: 'Supplier3',
        SVGTemplate: 'svg-supplier3'
   }
}

console.log(suppliers.findBy("id",1));

Here i've added function inside prototype of root Object.