How to sort an array of objects by multiple fields

How would you apply a sort on array of objects by multiple fields? This article offers an elegant solution.

Consider following JSON which represents objects stored in an array:

  var data = [{
    USER: "bob",
    SCORE: 2000,
    TIME: 32,
    AGE: 16,
    COUNTRY: "US"
  },
          {
    USER: "jane",
    SCORE: 4000,
    TIME: 35,
    AGE: 16,
    COUNTRY: "DE"
  },
          {
    USER: "tim",
    SCORE: 1000,
    TIME: 30,
    AGE: 17,
    COUNTRY: "UK"
  },
          {
    USER: "mary",
    SCORE: 1500,
    TIME: 31,
    AGE: 19,
    COUNTRY: "PL"
  },
          {
    USER: "joe",
    SCORE: 2500,
    TIME: 33,
    AGE: 18,
    COUNTRY: "US"
  },
          {
    USER: "sally",
    SCORE: 2000,
    TIME: 30,
    AGE: 16,
    COUNTRY: "CA"
  },
          {
    USER: "yuri",
    SCORE: 3000,
    TIME: 34,
    AGE: 19,
    COUNTRY: "RU"
  },
          {
    USER: "anita",
    SCORE: 2500,
    TIME: 32,
    AGE: 17,
    COUNTRY: "LV"
  },
          {
    USER: "mark",
    SCORE: 2000,
    TIME: 30,
    AGE: 18,
    COUNTRY: "DE"
  },
          {
    USER: "amy",
    SCORE: 1500,
    TIME: 29,
    AGE: 19,
    COUNTRY: "UK"
  }];

How do we create a function to sort the SCORE field in descending order, sort the TIME field in ascending order and also be able to sort the AGE field in ascending order using only JavaScript?

Consider the following predicate routine:

  function predicate() {
    var fields = [],
      n_fields = arguments.length,
      field, name, reverse, cmp;

    var default_cmp = function (a, b) {
        if (a === b) return 0;
        return a < b ? -1 : 1;
      },
      getCmpFunc = function (primer, reverse) {
        var dfc = default_cmp,
          // closer in scope
          cmp = default_cmp;
        if (primer) {
          cmp = function (a, b) {
            return dfc(primer(a), primer(b));
          };
        }
        if (reverse) {
          return function (a, b) {
            return -1 * cmp(a, b);
          };
        }
        return cmp;
      };

    // preprocess sorting options
    for (var i = 0; i < n_fields; i++) {
      field = arguments[i];
      if (typeof field === 'string') {
        name = field;
        cmp = default_cmp;
      } else {
        name = field.name;
        cmp = getCmpFunc(field.primer, field.reverse);
      }
      fields.push({
        name: name,
        cmp: cmp
      });
    }

    // final comparison function
    return function (A, B) {
      var a, b, name, result;
      for (var i = 0; i < n_fields; i++) {
        result = 0;
        field = fields[i];
        name = field.name;

        result = field.cmp(A[name], B[name]);
        if (result !== 0) break;
      }
      return result;
    };
  }

Now using the predicate function defined above we can do;

  data.sort(predicate({
    name: 'SCORE',
    reverse: true
  }, 'TIME', 'AGE'));

which gives the following output:

[ { USER: 'jane',  SCORE: 4000, TIME: 35, AGE: 16, COUNTRY: 'DE' },
  { USER: 'yuri',  SCORE: 3000, TIME: 34, AGE: 19, COUNTRY: 'RU' },
  { USER: 'anita', SCORE: 2500, TIME: 32, AGE: 17, COUNTRY: 'LV' },
  { USER: 'joe',   SCORE: 2500, TIME: 33, AGE: 18, COUNTRY: 'US' },
  { USER: 'sally', SCORE: 2000, TIME: 30, AGE: 16, COUNTRY: 'CA' },
  { USER: 'mark',  SCORE: 2000, TIME: 30, AGE: 18, COUNTRY: 'DE' },
  { USER: 'bob',   SCORE: 2000, TIME: 32, AGE: 16, COUNTRY: 'US' },
  { USER: 'amy',   SCORE: 1500, TIME: 29, AGE: 19, COUNTRY: 'UK' },
  { USER: 'mary',  SCORE: 1500, TIME: 31, AGE: 19, COUNTRY: 'PL' },
  { USER: 'tim',   SCORE: 1000, TIME: 30, AGE: 17, COUNTRY: 'UK' } ]

Neat, isn't it?

Credits

Based on following answer on stackoverflow: How to sort an array of objects by multiple fields?
Added here mostly for personal reference.

\m/