如何在循环（js）中从Map（obj）获取键和值？

Question

I try to get the key and values out of a map in a loop, in the second run the key and value is undefined. any ideas?

 let map = new Map(); map.set('{{NAME}}', 'Name'); map.set('{{CLASS}}', 'Sorc'); let keyIterator = map.keys(); let valIterator = map.values(); let counter = map.size; for (let i = 0; i < counter; i++){ console.log('Key: ' + keyIterator.next().value); console.log('Val: ' + valIterator.next().value); } 

Output:

Key: {{NAME}}

Val: Name

Key: undefined

Val: undefined

I hope its not a duplicate, but i couldnt find an clear answer to my problem.

Answer 1

You could iterate the entries of map by using a for ... of statement.

 let map = new Map(); map.set('{{NAME}}', 'Name'); map.set('{{CLASS}}', 'Sorc'); for (let [k, v] of map) { console.log('Key: ' + k); console.log('Val: ' + v); } 

Answer 2

Make it simple and just use the method of forEach from Map object.

 let map = new Map(); map.set('{{NAME}}', 'Name'); map.set('{{CLASS}}', 'Sorc'); map.forEach((val,key) => { console.log(`Key: ${key}`) console.log(`Val: ${val}`) })