TypeScript无法迭代关联数组

Question

I have a service which populates my associative array in typescript,

fun populateData(){
let tempArr;
tempArr = [];
this.service.get('Post', 1, 'true').subscribe(
        (response) => {
          this.loadingIcon = false;

          for (let i = 0; i < response.results.length; i++) {
             tempList = response.results[i]['tags'];
             for ( let iter of tempList){
               if ( iter in tempArr) {
                 tempArr[iter] = tempArr[iter] + 1;
               }else {
                 tempArr[iter] = 1;
               }
             }
          }
        },
        (error) => {
          if (error['status'] === 401) {
            localStorage.clear();
            this.router.navigateByUrl('/login');
          } else {
            this.router.navigateByUrl('/error');
          }
        }
      );
      console.log(tempArr);
        /*
          This function is inside a class, once I iterate get access to tempArr I will be assigning the tempArr data to a class variable like

       for (items in tempArr){
            this.data.push(items, tempArr[items]);
       }
        */
}

I'm able to populate my associative array with the service above which gives the following output in console,

I'm not able to iterate through this array, I tried a couple of methods like the following,

for ( const key in tempArr) {
      console.log(key + ':' + tempArr[key]);
    }

I want both they key and values from the array.

Answer 1

TypeScript generally assumes that the keys to arrays are numbers. What you were doing might work but it's not very idiomatic. I'm not going to rewrite your whole function but here are a few pointers:

When constructing your associative array (map for short from now on) you should try using an object instead of an array:

const tagCounts: { [key: string]: number } = {};
for (const result of response.results) {
    for (const tag of result.tags) {
        tagCounts[tag] = (tagCounts[tag] || 0) + 1;
    }
}

Then you can iterate the result with:

for (const tag of Object.keys(tagCounts)) {
    const count = tagCounts[tag];
    // Other stuff here
}

Or if you have polyfills for Object.entries then with:

for (const [tag, count] of Object.entries(tagCounts)) {
    // Other stuff here
}

Looking at your code, this.data.push also seems wrong: it will add a string and a number to your data array which is almost certainly not what you want. You might want to consider converting data to an object as well if you want to store key-value pairs.