Sorting on a custom order

For people looking to simply sort an array of strings in a custom order, try this function below:

// sorting fn
const applyCustomOrder = (arr, desiredOrder) => {
  const orderForIndexVals = desiredOrder.slice(0).reverse();
  arr.sort((a, b) => {
    const aIndex = -orderForIndexVals.indexOf(a);
    const bIndex = -orderForIndexVals.indexOf(b);
    return aIndex - bIndex;
  });
}

// example use
const orderIWant = ['cat', 'elephant', 'dog'];
const arrayToSort = ['elephant', 'dog', 'cat'];


applyCustomOrder(arrayToSort, orderIWant);

This will sort the array in the order specified. Two sample input / outputs to this function:

Example 1:

const orderIWant = ['cat', 'elephant', 'dog'] 
const arrayToSort = ['mouse', 'elephant', 'dog', 'cat'];
applyCustomOrder(arrayToSort, orderIWant); 
console.log(arrayToSort); // ["cat", "elephant", "dog", "mouse"]

Example 2:

const orderIWant = ['cat', 'elephant', 'dog'];
const arrayToSort = ['mouse', 'elephant', 'rabbit', 'dog', 'cat'];
applyCustomOrder(arrayToSort, orderIWant); 
console.log(arrayToSort); /* ["cat", "elephant", "dog", "mouse", 
"rabbit"] */

Try this:

var sortOrder = ['fruit','candy','vegetable'];   // Declare a array that defines the order of the elements to be sorted.
somethingToSort.sort(
    function(a, b){                              // Pass a function to the sort that takes 2 elements to compare
        if(a.type == b.type){                    // If the elements both have the same `type`,
            return a.name.localeCompare(b.name); // Compare the elements by `name`.
        }else{                                   // Otherwise,
            return sortOrder.indexOf(a.type) - sortOrder.indexOf(b.type); // Substract indexes, If element `a` comes first in the array, the returned value will be negative, resulting in it being sorted before `b`, and vice versa.
        }
    }
);

Also, your object declaration is incorrect. Instead of:

{
    type = "fruit",
    name = "banana"
}, // etc

Use:

{
    type: "fruit",
    name: "banana"
}, // etc

So, replace the = signs with :'s.

Improved version of Cerbrus' code:

var ordering = {}, // map for efficient lookup of sortIndex
    sortOrder = ['fruit','candy','vegetable'];
for (var i=0; i<sortOrder.length; i++)
    ordering[sortOrder[i]] = i;

somethingToSort.sort( function(a, b) {
    return (ordering[a.type] - ordering[b.type]) || a.name.localeCompare(b.name);
});