Count no of record as per key value from array using Javascript/Jquery

Question

I need to count the number of record present inside array of objects as per key value using Javascript/Jquery. I am explaining my code below.

var arrResult = [{"name":"jim","amount":34,"date":"11/12/2015"},
  {"name":"carl","amount":120.11,"date":"11/12/2015"},
  {"name":"jim","amount":45,"date":"12/01/2015"},
  {"name":"stacy","amount":12.00,"date":"01/04/2016"},
  {"name":"stacy","amount":34.10,"date":"01/04/2016"},
  {"name":"stacy","amount":44.80,"date":"01/05/2016"}
];

The above is my array of object. Here I need to count the no of record as per same name value and my expected output is given below.

var output=[
         {"name":"jim","count":2},
         {"name":"carl","count":1},
         {"name":"stacy","count":3}
]

Possible duplicate of [Javascript - Counting duplicates in object array and storing the count as a new object](https://stackoverflow.com/questions/45258566/javascript-counting-duplicates-in-object-array-and-storing-the-count-as-a-new) and [Count particular key value from array of object](https://stackoverflow.com/questions/38694939) — adiga, Mar 18 '19 at 09:46

score 3 · Accepted Answer · answered Mar 18 '19 at 09:48

You can use reduce:

var arrResult = [{"name":"jim","amount":34,"date":"11/12/2015"},
  {"name":"carl","amount":120.11,"date":"11/12/2015"},
  {"name":"jim","amount":45,"date":"12/01/2015"},
  {"name":"stacy","amount":12.00,"date":"01/04/2016"},
  {"name":"stacy","amount":34.10,"date":"01/04/2016"},
  {"name":"stacy","amount":44.80,"date":"01/05/2016"}
];

var output = arrResult.reduce((acc, curr) => {
  if (!acc.some(({ name }) => name == curr.name)) {
    acc.push({ name: curr.name, count: 1 });
  } else {
    acc.find(({ name }) => name == curr.name).count++;
  }
  return acc;
}, []);

console.log(output);

ES5 syntax:

var arrResult = [{"name":"jim","amount":34,"date":"11/12/2015"},
  {"name":"carl","amount":120.11,"date":"11/12/2015"},
  {"name":"jim","amount":45,"date":"12/01/2015"},
  {"name":"stacy","amount":12.00,"date":"01/04/2016"},
  {"name":"stacy","amount":34.10,"date":"01/04/2016"},
  {"name":"stacy","amount":44.80,"date":"01/05/2016"}
];

var output = arrResult.reduce(function(acc, curr) {
  if (!acc.some(function(e) {
    return e.name == curr.name;
  })) {
    acc.push({ name: curr.name, count: 1 });
  } else {
    acc.find(function(e) {
      return e.name == curr.name;
    }).count++;
  }
  return acc;
}, []);

console.log(output);

Yosvel Quintero · Answer 2 · 2019-03-18T10:00:16.903

You can use Object.values() combied Array.prototype.reduce():

const arrResult = [{"name":"jim","amount":34,"date":"11/12/2015"},{"name":"carl","amount":120.11,"date":"11/12/2015"},{"name":"jim","amount":45,"date":"12/01/2015"},{"name":"stacy","amount":12.00,"date":"01/04/2016"},{"name":"stacy","amount":34.10,"date":"01/04/2016"},{"name":"stacy","amount":44.80,"date":"01/05/2016"}];
const output = Object.values(arrResult.reduce((a, c) => {
  a[c.name] = a[c.name] ? {name: c.name, count: ++a[c.name].count} : {name: c.name, count: 1};
  return a;
}, {}));

console.log(output);

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Count no of record as per key value from array using Javascript/Jquery

2 Answers2