打字稿map.get返回未定义

Question

When I want get Object by key I have undefined each all element.

My Map :

nodesMaps : Map<number, Object> = [
{ key: "1", value: Object },
{ key: "2", value: Object },
{ key: "3", value: Object },
]

When I want get value of this map :

this.nodesMaps.get(1) // return undefined
this.nodesMaps.get("1") // return undefined

Answer 1

below code for me..

let map = new Map([
    [ "A", "AA" ],
    [ "B", "BB" ],
    [ "C", "CC" ]
]);

console.log(map.get("A"));

check this: https://jsfiddle.net/vipinmpd08/1b68eLdr/91920/

Answer 2

You've messed many things.

1. Even if you declared type Map , you assigned an Array value.
2. The array was array of objects, not array of arrays with length 2. etc.

Valid map creation should look like this:

 let nodesMap = new Map([ [1, 'foo'], [2, 'bar'], [3, 'baz'], ]) console.log(nodesMap.get(1)) // foo 

Answer 3

You can't assign properties on top of the fact they aren't objects, they are arrays, and you need to use new . Your code should look like:

// TypeScript
nodesMaps : Map<number, Object> = new Map([
  [ 1, Object ],
  [ 2, Object ],
  [ 3, Object ],
]);

Map Reference

 var nodesMaps = new Map([ [ 1, "Object 1" ], [ 2, "Object 2" ], [ 3, "Object 3" ], ]); $('button').on('click', function() { var key = $(this).data('key'); console.log("key :" + key); console.log("value: " + nodesMaps.get(key)); }); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <button data-key="1">1</button> <button data-key="2">2</button> <button data-key="3">3</button>