I'm rewriting an algorithm I originally wrote in C++, and looking for a similar implementation in JavaScript as what one would generally do in C++:

std::map<<std::string, std::vector<std::string>> my_map_of_vectors;

This is the closest I've got, but I'm struggling...

 var my_map = new Map();
 var array_history = [];

 // below within a for-loop...
 my_map.set(data_blob[row].s_col1,array_history.push({h_col1:data_blob[row].s_col2}));

And then to access the first element of the array, with a known key, I get nothing...

document.writeln(xer_map.get("GG1000").h_col1[0]);

Not sure where to go from here, any help is appreciated!