How can I do an asc and desc sort using underscore js

Question

I am currently using underscorejs for sort my json sorting  Now I have asked to do an ascending and descending sorting using underscore js  I do not see anything regarding the same in the documentation  How can I achieve this

User · Answer

The Array prototype s reverse method modifies the array and returns a reference to it  which means you can do this   var sortedAsc     sortBy collection   propertyName    var sortedDesc     sortBy collection   propertyName   reverse      Also  the underscore documentation reads      In addition  the Array prototype s methods are proxied through the chained Underscore object  so you can slip a reverse or a push into your chain  and continue to modify the array    which means you can also use  reverse   while chaining   var sortedDescAndFiltered     chain collection       sortBy  propertyName        reverse        filter   property  isGood         value

User · Answer

Descending order using underscore can be done by multiplying the return value by -1     Ascending Order    sortBy  2  3  1   function num       return num          1  2  3      Descending Order    sortBy  2  3  1   function num       return num   -1          3  2  1    If you re sorting by strings not numbers  you can use the charCodeAt   method to get the unicode value     Descending Order Strings    sortBy   a    b    c    function s        return s charCodeAt     -1

User · Answer

You can use  sortBy  it will always return an ascending list     sortBy  2  3  1   function num        return num          1  2  3    But you can use the  reverse method to get it descending   var array     sortBy  2  3  1   function num        return num       console log array       1  2  3  console log array reverse         3  2  1    Or when dealing with numbers add a negative sign to the return to descend the list     sortBy  -3  -2  2  3  1  0  -1   function num        return -num          3  2  1  0  -1  -2  -3    Under the hood  sortBy uses the built in  sort  handler        Default is ascending   2  3  1  sort        1  2  3      But can be descending if you provide a sort handler   2  3  1  sort function a  b           a   current item in array        b   next item in array     return b - a

User · Answer

Underscore Mixins  Extending on  emil lundberg s answer  you can also write a  mixin  if you re using Underscore to make a custom function for sorting if it s a kind of sorting you might repeat in an application somewhere   For example  maybe you have a controller or view sorting results with sort order of  ASC  or  DESC   and you want to toggle between that sort  you could do something like this   Mixin js    mixin       sortByOrder  function stooges  prop  order          if  String order       desc               return   sortBy stooges  prop  reverse            else if  String order       asc               return   sortBy stooges  prop           else             return stooges                     Usage Example  var sort order    asc   var stooges        name   moe   age  40       name   larry   age  50       name   curly   age  60      name   July   age  35      name   mel   age  38         mixin       sortByOrder  function stooges  prop  order        if  String order       desc             return   sortBy stooges  prop  reverse          else if  String order       asc             return   sortBy stooges  prop         else           return stooges                    find elements var banner       banner-message    var sort name btn      button sort-name    var sort age btn      button sort-age     function showSortedResults results  sort order  prop        banner empty        banner append   lt p gt Sorting      prop          sort order     lt  p gt  lt hr gt        each results  function r        banner append   lt li gt     r name     is    r age     years old  lt  li gt                 handle click and add class sort name btn on  click   function       sort order    sort order      asc      desc     asc        var sortedResults     sortByOrder stooges   name   sort order     showSortedResults sortedResults  sort order   name        sort age btn on  click   function         sort order    sort order      asc      desc     asc        var sortedResults     sortByOrder stooges   age   sort order     showSortedResults sortedResults  sort order   age         Here s a JSFiddle demonstrating this  JSFiddle for SortBy Mixin

User · Answer

Similar to Underscore library there is another library called as  lodash  that has one method  orderBy  which takes in the parameter to determine in which order to sort it  You can use it like    orderBy  collection    propertyName    desc     For some reason  it s not documented on the website docs

[javascript] How can I do an asc and desc sort using underscore.js?

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