Fixing issue with sorting which fails when different datatypes are given...

[eraser88]

... in the sortby list.

Fixing sorting issue mentioned below :

If i have objects like these :
[{"1", 100}, {"1", 1}, {"1", 2}, {"1", 200}]
If i sort the elements using both the columns then the result should be :
[{"1", 1}, {"1", 2}, {"1", 100}, {"1", 200}]
But in the current code the result that is displayed is :
[{"1", 1}, {"1", 100}, {"1", 2}, {"1", 200}]

[megawac]

this will call _.keys(a) on each iteration, you would want to cache this.

[megawac]

You may want to take a look at a relevant open pr, #1751 and issue #1768

This directly clashes with #1751

[jgonggrijp]

_.sortBy is for when you can reduce your values to a single string or number so that you can meaningfully apply the < operator. If you need to do something more fancy, pass your own custom comparator function to Array.prototype.sort instead. Note that this function is also available in Underscore OOP notation and in chains as _(yourArray).sort.

Related to #2848.