Javascript Select vector with the greatest number of items [closed]

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I have 4 arrays:

Note: Length of array length is different in any session

var Class_A = [8, 11, 3, 9, 11, 16, 16];
var Class_B = [2, 6, 12, 13, 20, 22, 33, 40, 50, 66, 77]; // Greatest length with 11 items,
var Class_C = [10, 14, 19];
var Class_D = [8, 2];

I need to select array with greatest number of items, (Class_B)

My expectation is:

var major = number major of array.length (in this case Class_B);

My code:

var major = max(Class_A.length > Class_B.length > Class_C.length > Class_D.length);

Edit An unorthodox solution, from a newbie but it works.

var Class_A = [8, 11, 3, 9, 11, 16, 54, 14, 5];
var Class_B = [2, 6, 12, 13, 20, 22, 33, 40, 50, 66, 77, 16, 7]; // Greatest length with 11 items,
var Class_C = [10, 14, 19];
var Class_D = [8, 2];

var Classes = [];
                    Classes.push(Class_A.length) ;
                    Classes.push(Class_B.length) ;
                    Classes.push(Class_C.length) ;
                    Classes.push(Class_D.length) ;

                console.log("Lenght of 4 arrays>"+Classes);
                
                Classes.sort(function(a, b) { // order by major number
                    return a - b;
                });
        
                Classes.reverse(); // reverse array
        
                console.log("Total>"+Classes); // print sort by major number

                console.log("Major>"+Classes[0]); // Works => the magic number that I need

Answer

Put all your arrays in an array.

classes = [Class_A, Class_B, Class_C, Class_D];

Then, to get the largest one:

classes.reduce((acc, curr) => curr.length > acc.length ? curr : acc);
// => [2, 6, 12, 13, 20, 22, 33, 40, 50, 66, 77]

EDIT:

Or, if you want length of the largest array:

classes.reduce((acc, curr) => curr.length > acc ? curr.length : acc, 0);
// => 11


Source: stackoverflow