TypeScript unable to loop through object with string keys

My TypeScript service is responsible for populating an associative array:

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]);
       }
        */
}

Upon execution, the console displays the populated associative array:

https://i.sstatic.net/lqNzG.png

Despite the successful population, I encountered difficulty iterating through the array. I attempted various methods, such as:

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

I am seeking a solution to retrieve both keys and values from the array.

Answer №1

In TypeScript, it is common practice to use objects rather than arrays when creating associative arrays (referred to as maps). It may be possible for your current method to work, but it is not the most standard approach. Here are some suggestions to improve your code:

Instead of using an array, consider using an object when constructing your associative array:

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

You can then iterate through the results using:

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

If you have polyfills for Object.entries, you can also use:

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

In your existing code, using this.data.push seems incorrect as it will add a string and a number to your data array. Consider converting data to an object if you intend to store key-value pairs instead.

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