Le max de colonne

const A = [ [4,5,10], [1,20,3], [0,5,-6], [1,200,3], ];

MAX des colonnes : 4,200,10

Avant Map/reduce

function maxi(A){

      let maxC = [];

      for( let c=0; c < A[0].length; c++){ 

          let max = -Infinity; 

          for ( let l=0; l < A.length; l++){

                 if ( max < A[l][c] ) max = A[l][c];

          }

          maxC.push(max);

      }

      return maxC;

}

code

Après Map/reduce

let AMax = A[0].map( function (_,col) {

   return A.reduce( function (acc,lig) {    

     return Math.max(acc,lig[col])

   } ,-Infinity)

});

code