How to sort an array of objects based on the substring of property values

Question

How can I sort the following array, in a custom order, based on the prop2 's last 3 letters that have to be in this order 'ABR', 'FDE', 'ZFR' and also in descending order 'ZFR', 'FDE', 'ARB' for another array.

Sample input:

const arr = [
  { prop1: 3, prop2: '3FDE' },
  { prop1: 4, prop2: '5ZFR' },
  { prop1: 5, prop2: '7ABR' }
]

Expected output:

const arr1 = [
  { prop1: 5, prop2: '7ABR' },
  { prop1: 3, prop2: '3FDE' },
  { prop1: 4, prop2: '5ZFR' }
]

and

const arr2 = [
  { prop1: 4, prop2: '5ZFR' },
  { prop1: 3, prop2: '3FDE' },
  { prop1: 5, prop2: '7ABR' }
]

Answer 1

• Using Array#sort , iterate over the array to sort it
• In every iteration, use String#substr to get the last 3 characters and String#localeCompare to compare the two strings

 const arr = [ { prop1: 3, prop2: '3FDE' }, { prop1: 4, prop2: '5ZFR' }, { prop1: 5, prop2: '7ABR' } ]; const _getLastThree = (str = '') => str.substr(str.length - 3); const res = arr.sort(({ prop2: a }, { prop2: b }) => _getLastThree(a).localeCompare(_getLastThree(b)) ); console.log(res);

Answer 2

Just use .localeCompare() in combination with .slice() :

 const arr=[ {prop1:5, prop2:'7ABR'}, {prop1:3, prop2:'3FDE'}, {prop1:4, prop2:'5ZFR'}, ] var ascArr,dscArr; console.log(ascArr=arr.slice(0).sort((a,b)=>a.prop2.slice(-3).localeCompare(b.prop2.slice(-3)))); // for descending order just do console.log(dscArr=arr.slice(0).sort((a,b)=>-a.prop2.slice(-3).localeCompare(b.prop2.slice(-3)))); // or reverse the resulting array with console.log(dscArr=ascArr.reverse());

Please note that the two slice() methods belong to different prototypes : .slice(0) is an Array method that essentially creates a flat copy of the original array while .slice(-3) is a String method that "shaves off" the last three characters of the string.

Answer 3

You can use the Array#sort , String#substring or String#slice or String#substr and the String#localCompare methods as follows:

• substring

 const arr = [ {prop1:4, prop2:'5ZFR'}, {prop1:5, prop2:'7ABR'}, {prop1:3, prop2:'3FDE'} ]; const output = arr.sort( (a,b) => a.prop2.substring(1).localeCompare( b.prop2.substring(1) ) ); console.log( output );

With slice or substr you can use a negative n to indicate the last n characters:

 const arr = [ {prop1:4, prop2:'5ZFR'}, {prop1:5, prop2:'7ABR'}, {prop1:3, prop2:'3FDE'} ]; const output = arr.sort( (a,b) => a.prop2.slice(-3).localeCompare( b.prop2.slice(-3) ) ); console.log( output );