CODEWITHSUNDEEP
javascriptecmascript-6
Mellisa
Mellisa

Reputation: 605

Push array of object instead of its value

var items = [{
    "name": "James",
    "gender": "boy"
}, {
    "name": "Sam",
    "gender": "boy"
}, {
    "name": "Alice",
    "gender": "girl"
}];

I want to add count for the gender into a array of object above. like for boy it's 2, and girl it's 1. I've done below part where it return the category.

var genderList = [];
for(var i = 0; i < items.length ; i++){
      if(genderList.indexOf(items[i].gender) < 0){
        genderList.push(items[i].gender);
       }
}

how can I produce the result like this?

[{"name":"boy","count":2},{"girl","count":1}]

Upvotes: 1

Views: 91

Answers (3)

nnnnnn
nnnnnn

Reputation: 150040

You can use the array .reduce() method to count values - I'd suggest getting output in a structure like {"boy": 2, "girl": 1} rather than the array of objects you showed, because it's simple and efficient to create, update, and read.

You could then convert it to the format you've shown:

var items = [
  { "name": "James", "gender": "boy"},
  { "name": "Sam", "gender": "boy"},
  { "name": "Alice", "gender": "girl"}
];

var genderCount = items.reduce(function(a, c) {
  a[c.gender] = (a[c.gender]||0) + 1;
  return a;
}, {});
console.log(JSON.stringify(genderCount));

var asArray = Object.keys(genderCount).map(v => ({ name: v, count: genderCount[v] }));
console.log(JSON.stringify(asArray));

If you're not familiar with .reduce(), it does the same thing as the loop below, except without needing to create extra working variables in the current scope:

var items = [
  { "name": "James", "gender": "boy"},
  { "name": "Sam", "gender": "boy"},
  { "name": "Alice", "gender": "girl"}
];

var genderCount = {}
for (var i = 0; i < items.length; i++) {
  genderCount[items[i].gender] = (genderCount[items[i].gender]||0) + 1;
}
console.log(JSON.stringify(genderCount));

// then as above to get your array of objects output:
var asArray = Object.keys(genderCount).map(v => ({ name: v, count: genderCount[v] }));
console.log(JSON.stringify(asArray));

NOTE: In the above examples I'm using JSON.stringify() only to make it fit in the console on one line, it's not part of the counting/conversion process.

Upvotes: 1

Turnipdabeets
Turnipdabeets

Reputation: 6005

var items = [
  { "name": "T", "gender": "other"},
  { "name": "James", "gender": "boy"},
  { "name": "Sam", "gender": "boy"},
  { "name": "Alice", "gender": "girl"}
];

taking the previous item and comparing the gender type. If it exists we add 1, if doesn't then we create it and add 1.

var genderTypes = items.reduce(function(prev, cur) {
  prev[cur.gender] = (prev[cur.gender]||0) + 1;
  return prev;
}, {});

console.log('genderTypes', genderTypes)

next we take the keys from the object and separate them out into gender and count

var separateNameAndCount = Object.keys(genderTypes).map(type => ({ name: type, count: genderTypes[type] }));

console.log('separateNameAndCount', separateNameAndCount)

finally we convert the object to json format

console.log(JSON.stringify(separateNameAndCount));

Upvotes: 1

Hikmat Sijapati
Hikmat Sijapati

Reputation: 6994

Try like this.use Array.map

var items = [{
    "name": "James",
    "gender": "boy"
}, {
    "name": "Sam",
    "gender": "boy"
}, {
    "name": "Alice",
    "gender": "girl"
}];
var b=0,g=0;
items.map((item)=>(item.gender=="boy")?b++:g++);
var finalArray = [{"name":"boy","count":b},{"name":"girl","count":g}]
console.log(finalArray);

Upvotes: 0

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