向对象数组添加新属性

Question

I have a list of entities where each entity is as follows:

var entity = {
  position: 'X',
  varA: [{ id: 1, name: 'A1' }, { id: 2, name: 'A2' }],
  varB: [{ id: 1, name: 'B1' }, { id: 2, name: 'B2' }],
  varC: [{ id: 1, name: 'C1' }, { id: 2, name: 'C2' }],
}

For each entity I need to add a property 'names' that is:

entity.names = [varA[0].name, varB[0].name, varC[0].name];

The problem is that varA, varB or varC can in some cases be undefined or have no values. So I tried:

vm.entities.map(function(entity) { 

  entity.names = [entity.varA[0], entity.varB[0], entity.varC[0]].filter(e => e).map(({name:n}) => n);

  return entity; 

});

The expected output is:

entity.names = [ 'A1', 'B1', 'C1' ]

However, I am unable to minify my javascript due to this code line:

entity.names = [entity.varA[0], entity.varB[0], entity.varC[0]].filter(e => e).map(({name:n}) => n);

What am I doing wrong and is there a better way to do this?

Answer 1

You could iterate all keys of the object and take only arrays for collecting names for the new property.

For getting only one name out of the array, you could use Array#some and exit if a name of an array is found.

 var entity = { position: 'X', varA: [{ id: 1, name: 'A1' }, { id: 2, name: 'A2' }], varB: [{ id: 1, name: 'B1' }, { id: 2, name: 'B2' }], varC: [{ id: 1, name: 'C1' }, { id: 2, name: 'C2' }] }; entity.names = Object.keys(entity).reduce(function (r, k) { if (Array.isArray(entity[k])) { entity[k].some(function (o) { if (o && typeof o === 'object' && o.name) { r.push(o.name); return true; } }); } return r; }, []); console.log(entity); 

 .as-console-wrapper { max-height: 100% !important; top: 0; }