TypeScript and Angular: Error Encountered when Trying to Combine Two Arrays

I'm attempting to combine two arrays of the same type that are nested within a "parent" array. The end goal is to flatten the structure.

Below is the code I have been using:

ngOnInit() {
    this.Logs.getAllLogs()
      .subscribe(logs => {
        this.Logs = Object.values(logs);
        console.log('First: ', this.Logs[0]);
        console.log('Second: ', this.Logs[1]);
        this.mergedLogs = this.Logs[0].concat(this.Logs[1]);
        console.log('Together: ', this.mergedLogs);
      });   

However, I encountered this error:

ERROR TypeError: _this.Logs[0].concat is not a function

UPDATE: After receiving suggestions from users to use a spread operator, I updated the code as follows:

ngOnInit() {
    this.Logs.getAllLogs()
      .subscribe(logs => {
        this.Logs = Object.values(logs);
        console.log('First: ', this.Logs[0]);
        console.log('Second: ', this.Logs[1]);
        this.mergedLogs = [...this.Logs[0], ...this.Logs[1]];
        console.log('Together: ', this.mergedLogs);
      });
  }

Despite making these changes, I still encounter the same error. When I comment out the line where the arrays are merged, the page refreshes without issue, indicating it's not a caching problem.

Answer №1

Instead of using the concat() method to combine arrays, consider using the spread operator (...) if you're dealing with arrays of the same type.

You can implement it by following this code snippet -

  this.combinedArrays = [...this.arrays[0],...this.arrays[1]);

For further details and examples, refer to the link provided below

Answer №2

Utilize the spread operator in the following manner:

By implementing this code, you can merge arrays: [...this.Logs[0], ...this.Logs[1]];

Answer №3

One glaring error that was clearly evident is your usage of this.Logs instead of logs within the subscribe callback.

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