遍历对象并获取键以重新分配它们

Question

I have a small snippet of code. This code will grab an object that has key value pairs. I have another object that is an empty array. I want to iterate over the object and create arrays of each value pair in from the collection and push each array to the empty array object.

What I am currently doing is passing in a collection (empty array) and a function. I want to create another function that wil apply a function to each item in the object. I am able to grab each objects value and empty collection. I need to grab each values key and create an array out it.

    var letters = {d: 'dog', e: 'elephant', f: 'flotsam'};
    var iterations = [];

    _.each(letters, function(value, property) {
      iterations.push([value, property]);
    });

    expect(iterations).to.eql([
      ['dog', 'd'],
      ['elephant', 'e'],
      ['flotsam', 'f']
    ]);

// this is the function that accepts a empty collection and callback 
_.each = function(collection, iterator) {
    console.log(Object.keys(collection))
    for (var i = 0; i < collection.length; i++){
      // I want to insert the key where the (i) is located below
      iterator(collection[i],i , collection);
    };
  };

I want to grab each key when cycling through the passed collection and insert that key where the (i) is two lines from the bottom of the code snippet below. I tried a few different things but they are not working.

Answer 1

Using native forEach :

_.each = function(collection, iterator) {
    Object.keys(collection).forEach(x => iterator(collection[x], x, collection));
};

Answer 2

If you want to get the key value pair you can use the map method on the keys of the object for example:

const myArray = Object.keys(letters).map((key)=>[letters[key], key])

If this is not what you want you can tell me:

Answer 3

isn't only this is enough

_.map(letters, (v,k)=>[v,k])

Remember, you can use all the underscore/lodash collection functions on object directly with value/key pairs.

 var letters = {d: 'dog', e: 'elephant', f: 'flotsam'}, iterations = _.map(letters, (v,k)=>[v,k]); console.log('Iterations: ', iterations); 

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