How to get length of TypeScript Map<k, v>?(Error: Map.size gives undefined)

Question

I have Map in my angular component as key being object of class Group and value being an array of class Match which basically says group and matches that will take place among the group members of that group. .

Map< Group, Match[]>

I want to have the total number of entries in the map and length of match array as well. How do I do that?

I've tried map.size and map.values().next().length

Answer 1

Sometimes newMap.size gives undefined value. Use this simple code to find map size.

Object.keys(newMap).length 

Answer 2

I encountered a similar problem. You have to call the Map constructor. My original code was:

 let a : Map<string,number> = {} as Map<string,number>;
 Map.size //undefined

If you call it properly, then works:

let a: Map<string,number> = new Map<string,number>();
Map.size //the right size