javascript - Building and updating array objects -

i'm working on simple registration system displays number of seats available in particular workshop. it's built in google apps script runs javascript syntax.

i build array of class objects user when log in. 1 of object keys seats, shows available number of spots left in workshop. that, compare master list of classes max number of registrants current registration list.

class object

[{    date: 4/10/2017,   title: "workshop 1",   desc: "a string description 1",   seats: "" }] 

google sheets table

| date      | title      | description                | seats |   | |-----------|------------|----------------------------|-------|---| | 4/10/2017 | workshop 1 | string description 1 | 20    |   | | 5/10/2017 | workshop 2 | string description 2 | 25    |   | 

current registrations

| user  | class0    | class1    | |-------|-----------|-----------| | user1 | 4/10/2017 |           | | user2 | 4/10/2017 | 5/10/2017 | |       |           |           | 

script

// set count variable   var count;    // sessions user not registered   for(var i=0; i<sessions.length; i++) {      // class in master list     for(var j=0; j<allsessionsdata.length; j++) {        // find stored date in master list       var date = allsessionsdata[j][0];        // match session dates find max seats       if(sessions[i].date === date) {         sessions[i].seats = allsessionsdata[j][5];       }      }   }    // reopen sessions loop current counts   for(var i=0; i<sessions.length; i++) {     var count = sessions[i].seats;      // current 2d registrations array     for(var j=0; j<allregsdata.length; j++) {       for(var k=0; k<allregsdata[j].length; k++) {          if(sessions[i].date === allregsdata[j][k]) {           count--;           sessions[i].seats = count;         }       }     }   }   // return updated array   return sessions; } 

the function return 18 4/10 date , 24 5/10. script working i'm wondering if should condensed 1 loop , why. know "best practice" subjective, feels redundant build 1 array reopen within same function.

the user classes table has bad design, since cannot accomodate users take 3 classes. following preferable , lead easier code:

| user  | class     | |-------|-----------| | user1 | 4/10/2017 |        | user2 | 4/10/2017 |  | user2 | 5/10/2017 | |       |           |  

also, without count , use --sessions[i].seats; sessions[i].seats == count