How to keep the sequence in javascript Map?

Question

i have myData map as below

 var myData =  new Object();

 myData[10427] = "Description 10427";
 myData[10504] = "Description 10504";
 myData[10419] = "Description 10419";

but now when i iterate over myData, i don't get same sequnce in chrome and IE works fine in firefox. It iterates in ascending order of key

for (var key in myData) {
  alert("key is"+key);
  }

i get the output in ascending order in alert as 10419,10427,10504

How i can make sure to iterate in same order as data as inserted in map?

Answer 1

ES6 Maps preserves the insertion order.

The set method is used for setting the key value pairs

var myData = new Map();
myData.set(10427, "Description 10427");
myData.set(10504, "Description 10504");
myData.set(10419, "Description 10419");

Map keys and values are printed using

myData.forEach((value,key) => console.log(key, value));

This will print the keys and values in the insertion order