javascript-按多个条件排序-首先按另一个数组，然后按内部的另一个属性

Question

I have an array of objects as below and need to sort it in such fashion that items with c comes first, then y , then s. And in that too, for eg in c, it should be sorted by counter ie c- counter 1, c- counter 2.

var data = [ { age:7, counter: 1, code: 'c'},
     { age:5, counter: 2, code: 'c'},
     { age:4, counter: 3, code: 'c'},
     { age:19, counter: 2, code: 'y'},
     { age:22, counter: 1, code: 'y'},
     { age:57, counter: 1, code: 's'},
     { age:80, counter: 2, code: 's'}
    ]

Upon looking on SO, I was able to sort by c, y, s as below, but could not do another sort for counter inside. How can I do that.

var order =[c,y,s];
data.sort(function(a,b){
        return order.indexOf(a.code) < order.indexOf(b.code) ? -1:1;
})

Answer 1

You could use an object for the order of code and then sort by count.

 var data = [{ age: 7, counter: 1, code: 'c' }, { age: 5, counter: 2, code: 'c' }, { age: 4, counter: 3, code: 'c' }, { age: 19, counter: 2, code: 'y' }, { age: 22, counter: 1, code: 'y' }, { age: 57, counter: 1, code: 's' }, { age: 80, counter: 2, code: 's' }]; data.sort(function (a, b) { var order = { c: 1, y: 2, s: 3 }; return order[a.code] - order[b.code] || a.counter - b.counter; }); console.log(data); 

Answer 2

You need to specify array as

var order =['c', 'y', 's'];

otherwise c, y and s needs to be variables.

Also, you need to compare the counter variables as well if codes are equal

data.sort(function(a,b){
   if ( a.code == b.code )
   {
        return a.counter - b.counter;
   }
   else
   {
       return order.indexOf(a.code) - order.indexOf(b.code);
   }
})

Answer 3

This is a simple way to sort by counter:

var order = [ 'c', 'y', 's' ];

data.sort(function (a,b) {
    var o;

    if (order.indexOf(a.code) === order.indexOf(b.code))
    {
        o = a.counter - b.counter;
    } else {
        o = order.indexOf(a.code) - order.indexOf(b.code);
    }

    return o;
});

Answer 4

This is a dynamic way which allows you to add your conditions to be compare one after another.

 var data = [{ age: 7, counter: 1, code: 'c' }, { age: 5, counter: 2, code: 'c' }, { age: 4, counter: 3, code: 'c' }, { age: 19, counter: 2, code: 'y' }, { age: 22, counter: 1, code: 'y' }, { age: 57, counter: 1, code: 's' }, { age: 80, counter: 2, code: 's' }]; Array.prototype.orderBy = function(...expresions) { var arr = this; return this.sort((a, b) => { var result; expresions.every(ex => (result = ex(a) - ex(b)) === 0) return result; }); } var codeOrder = { c: 1, y: 2, s: 3 }; var result = data .orderBy(i => codeOrder[i.code], i => i.counter) console.log(result); 

How it works

The usage is simple:

dataArray.sortBy(ex1[, ex2[, ex3]])

every arguments of this method is a function which accepts one item from dataArray as input and returns a number related to that item. if any of expressions return same value with respect to adjacent item then evaluation continues with next expression on item and adjecent until they return different result or there is no other expression to test.