Filtering and Referencing Array to an Object Array in Javascript

Question

I have 2 arrays:

Time Stamp Array:

var timeStamp = [["0:00","1:00"], ["2:00","3:00"]];

Time Label Reference:

var timeLabels = [
 { name: "0:00", present: true, label: ["0:00", "1:00"], alterName:"" }, 
 { name: "1:00", present: true, label: ["1:00", "2:00"], alterName:"" }, 
 { name: "2:00", present: true, label: ["2:00", "3:00"], alterName:"" }]

I wanted to use Lodash to filter through the TimeStamp array but the methods I want are exclusive to object arrays. I currently have a for loop and it is not very elegant.

Ultimately, I want to create a TimeLabels object array thats present field is set to True or False if the time is present in the first index of timeStamp.

Referencing the Time Stamp Array above, the result would be:

var timeResult = [
 { name: "0:00", present: true, label: ["0:00", "1:00"], alterName:"" }, 
 { name: "1:00", present: false, label: ["1:00", "2:00"], alterName:"" }, 
 { name: "2:00", present: true, label: ["2:00", "3:00"], alterName:"" }]

I'm more used to using lodash but I'm wondering if other methods would be better to construct the solution or if a for loop, which I'm currently using is ok.

What methods in lodash are you talking about? There shouldn't be any that are exclusive to arrays. Also, most methods in lodash you can achieve native in arrays in modern browsers i.e. map, reduce, filter, forEach — dpix
– dpix, Commented Feb 21, 2017 at 3:53

Hikmat Sijapati · Accepted Answer · 2017-02-21 04:25:52Z

1

Foreach elment inside timeLabels use indexOf to determine whether label is present or not in timestamp.To use indexOf you have to convert object into string using JSON.stringify().

var timeLabels = [
 { name: "0:00", present: true, label: ["0:00", "1:00"], alterName:"" }, 
 { name: "1:00", present: true, label: ["1:00", "2:00"], alterName:"" }, 
 { name: "2:00", present: true, label: ["2:00", "3:00"], alterName:"" }];
 
 timeStamp = [["0:00","1:00"], ["2:00","3:00"]];
 
results = timeLabels.forEach(function(res){
 label = JSON.stringify(res.label);//converts into string
 ts = JSON.stringify(timeStamp);//converts into string
 if(ts.indexOf(label)>=0){ //checks whether label is present or not
 res.present = true;
 }
 else{
 res.present = false;
 }
});
console.log(timeLabels);

answered Feb 21, 2017 at 4:25

Hikmat Sijapati

6,9691 gold badge11 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

ryeballar · Accepted Answer · 2017-02-21 04:58:52Z

We can use map to iterate and return each of the transformed item. Notice that I used assign instead of manually assigning the present property, this is to avoid mutating the objects inside the timeLabels collection. Lastly, we use the combination of intersectionWith and isEmpty() to get the present value (Note that the resulting value is negated).

var timeResult = _.map(timeLabels, function(item) {
  return _.assign({}, item, {
    present: !_(timeStamp)
      .intersectionWith([item.label], _.isEqual)
      .isEmpty()
  });
});

var timeStamp = [
  ["0:00", "1:00"],
  ["2:00", "3:00"]
];

var timeLabels = [{
    name: "0:00",
    present: true,
    label: ["0:00", "1:00"],
    alterName: ""
  },
  {
    name: "1:00",
    present: true,
    label: ["1:00", "2:00"],
    alterName: ""
  },
  {
    name: "2:00",
    present: true,
    label: ["2:00", "3:00"],
    alterName: ""
  }
];

var timeResult = _.map(timeLabels, function(item) {
  return _.assign({}, item, {
    present: !_(timeStamp)
      .intersectionWith([item.label], _.isEqual)
      .isEmpty()
  });
});

console.log(timeResult);

body > div { min-height: 100%; top: 0; }

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

Yonghoon Lee · Accepted Answer · 2017-02-21 04:21:08Z

0

var tmpTimeStamp = timeStamp.map(function(ts){ return ts[0]+"_"+ts[1] });
timeResult = timeResult.map(function(t){
  t.present = tmpTimeStamp.indexOf(t.label[0]+"_"+t.label[1]) > -1;
  return t;
});

answered Feb 21, 2017 at 4:21

Yonghoon Lee

2,5041 gold badge15 silver badges8 bronze badges

Collectives™ on Stack Overflow

Filtering and Referencing Array to an Object Array in Javascript

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related