为让循环不起作用？

Question

When I use for in loop, it works, and for of loop just doesn't get anything :( Here is my code

'use strict'

var match_table = [
  {'project': 'Laveral', 'template': 'Blade'},
  {'project': 'Ember.js', 'template': 'Handlebars'},
  {'project': 'Meteor', 'template': 'Handlebars'},
];

// count project number by template
var templateMap = new Array();
match_table.forEach(function(listItem){
  var template = listItem['template'];
  if (!templateMap[template]) {
    templateMap[template] = new Object();
  }
  templateMap[template]['name'] = template;
  if (templateMap[template]['count']) {
    templateMap[template]['count']++;
  } else {
    templateMap[template]['count'] = 1;
  }
});

//console.log(templateMap);

// for loop fails
for (let value of templateMap) {
  console.log(value);
}

templateMap.forEach(function(item) {
  console.log(item);
})

also forEach doesn't output anything either~?!

Answer 1

for-of cannot iterate through objects (since they are not iterable as per the standard).

So you either must use the good old for-in

OR

Use the non-standardised yet Object.entries() :

for (const [key, value] of Object.entries(obj)) {
    console.log(key, value);
}

templateMap in your case is an object, not an array, since you assign string keys into it (and JS arrays indexes are numeric within [0; 2^32-1) range).

Answer 2

Is template numeric? It looks like you're about to misuse an Array as an Object. Try templateMap.push(new Object()) to append to the array instead.