javascript - How to add object property in map -

i tried add property in map loop seems updated on copy not object itself.

my_array.map(function(d){   d.size = do_seomthing });

you have reassign my_array

my_array = my_array.map(function(d){   d.size = [somevalue];    return d; // per comment });

another way directly rewrite array using array initial value (see mdn link more on that):

my_array.map(function(d, i){   this[i].d.size = [somevalue]; }, my_array);

the map() method creates new array results of calling provided function on every element in array.

O9