Question

124

Sort array on key value

rated 0 times [ 127] [ 3] / answers: 1 / hits: 84246 / 11 Years ago, mon, may 20, 2013, 12:00:00

I have a function which sorts by name currently and an array of value / key pairs.

I wonder how can I pass the key on which sort is being performed so I can call the same function every time like so:

var arr = [{name:'bob', artist:'rudy'},

           {name:'johhny', artist:'drusko'},

           {name:'tiff', artist:'needell'},

           {name:'top', artist:'gear'}];



sort(arr, 'name');   //trying to sort by name

sort(arr, 'artist'); //trying to sort by artist



function sort(arr) {

  arr.sort(function(a, b) {

    var nameA=a.name.toLowerCase(), nameB=b.name.toLowerCase();

    if (nameA < nameB) //sort string ascending

      return -1;

    if (nameA > nameB)

      return 1;

    return 0; //default return value (no sorting)

   });          

}

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leslijessalyng

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answered 11 Years ago kiyam · Accepted Answer

[edit 2020/08/14] This was rather an old answer and not very good as well, so simplified and revised.

Create a function that returns the sorting lambda (the Array.prototype.sort callback that does the actual sorting). That function can receive the key name, the kind of sorting (string (case sensitive or not) or numeric) and the sorting order (ascending/descending). The lambda uses the parameter values (closure) to determine how to sort.

const log = (...strs) => 

  document.querySelector(pre).textContent += `n${strs.join(n)}`;

const showSortedValues = (arr, key) => 

  ` => ${arr.reduce((acc, val) => ([...acc, val[key]]), [])}`;

  

// the actual sort lamda factory function

const sortOnKey = (key, string, desc) => {

  const caseInsensitive = string && string === CI;

  return (a, b) => {

    a = caseInsensitive ? a[key].toLowerCase() : a[key];

    b = caseInsensitive ? b[key].toLowerCase() : b[key];

    if (string) {

      return desc ? b.localeCompare(a) : a.localeCompare(b);

    }

    return desc ? b - a : a - b;

  }

};



// a few examples

const onNameStringAscendingCaseSensitive = 

  getTestArray().sort( sortOnKey(name, true) );

const onNameStringAscendingCaseInsensitive = 

  getTestArray().sort( sortOnKey(name, CI, true) );

const onValueNumericDescending = 

  getTestArray().sort( sortOnKey(value, false, true) );



// examples

log(`*key = name, string ascending case sensitive`,

  showSortedValues(onNameStringAscendingCaseSensitive, name)

);



log(`n*key = name, string descending case insensitive`,

  showSortedValues(onNameStringAscendingCaseInsensitive, name)

);



log(`n*key = value, numeric desc`, 

  showSortedValues(onValueNumericDescending, value)

);



function getTestArray() {

  return [{

    name: 'Bob',

    artist: 'Rudy',

    value: 23,

  }, {

    name: 'John',

    artist: 'Drusko',

    value: 123,

  }, {

    name: 'Tiff',

    artist: 'Needell',

    value: 1123,

  }, {

    name: 'Top',

    artist: 'Gear',

    value: 11123,

  }, {

    name: 'john',

    artist: 'Johanson',

    value: 12,

  }, ];

}

<pre></pre>