tap vs. mapObject

map-object-with-keys.js

_.mixin({
    mapObjectWithKeys: mapObjectWithKeys
});


/////////////////////

/**
 * is similar to `.mapObject` but just apply `iteratee` for properties have key in `keys`
 * Eg:
 * var obj = {'x':'a', 'y':'5', 'z':'6'};
 * _.mapObjectWithKeys(obj, parseInt, 'y', 'z') // {'x':'a', 'y':5, 'z':6}
 * // _.mapObjectWithKeys(obj, parseInt, ['y', 'z']) // {'x':'a', 'y':5, 'z':6}
 * @param {Object} obj
 * @param iteratee
 * @returns {Object}
 */

tap-vs-mapobject.md

I have a object

var obj = {
  x: 'abc',
  y: '6',
  z: '8'
};

I want to convert y and z to int type. There are 2 ways:

• Using .mapObject, I choose the way because when I want more keys, just change keys variable, no more lines

var keys = ['y', 'z'];
_.mapObject(obj, function(value, key) {
  return _.contains(keys, key) ? parseInt(value) : value;
});

• Using .tap, just reference, If I want more keys, more lines, more code

_.tap(obj, function(obj){
  obj.y = parseInt(obj.y);
  obj.z = parseInt(obj.z);
});