Typescript error: Trying to use the `push` method on an undefined property

Question

Typescript error: Trying to use the `push` method on an undefined property

I am facing difficulties when trying to push a value into an array. Below is the code snippet I am working on: My goal is to localize an Angular application, but the data needed for translation is not stored in the HTML file - it's in the ts file.

export class EventReportModalComponent implements OnInit {
  reasons: Array<string>;
  reasonsKeys = [
    'report.reason.nudity',
    'report.reason.hate-speech',
    'report.reason.violence',
    'report.reason.bullying',
    'report.reason.false-information',
    'report.reason.undesirable-content',
    'report.reason.other',
  ];

  constructor(
    private translate: TranslateService
  ) {
    let reasons;
    for (let item of this.reasonsKeys) {
      this.translate.get(item).subscribe(res => {
        reasons.push(res);
      });
    }

    this.reasons = reasons;
  }

  ngOnInit(): void {
  }
}

An error occurred:

TypeError: Cannot read property 'push' of undefined

I am confused about how to solve this issue in JavaScript. Can someone help me identify my mistake?

angular typescript ngx-translate

Answer 1

Answer №1

Your code has a couple of issues that need to be addressed.

Undefined variable reasons

To solve this, make sure to initialize reasons as an empty array before attempting to add any elements to it: let reasons = [];

Handling asynchronous functions

The usage of this.translate.get suggests it is an asynchronous function. Therefore, directly assigning it to this.reasons might not yield the desired result. Instead, consider dynamically adding items to the final object.

let reasons;
for (let item of this.reasonsKeys) {
  this.translate.get(item).subscribe(res => {
    reasons.push(res);
  });
}

this.reasons = reasons; // The array remains empty due to the asynchronous nature of translate.get

Have you considered pushing elements directly into this.reasons instead?

Answer 2

Your code has a couple of issues that need to be addressed.

Undefined variable reasons

To solve this, make sure to initialize reasons as an empty array before attempting to add any elements to it: let reasons = [];

Handling asynchronous functions

The usage of this.translate.get suggests it is an asynchronous function. Therefore, directly assigning it to this.reasons might not yield the desired result. Instead, consider dynamically adding items to the final object.

let reasons;
for (let item of this.reasonsKeys) {
  this.translate.get(item).subscribe(res => {
    reasons.push(res);
  });
}

this.reasons = reasons; // The array remains empty due to the asynchronous nature of translate.get

Have you considered pushing elements directly into this.reasons instead?

Answer 3

Answer №2

Start by setting the reasons variable to an empty array in the constructor.

let reasons = [];

Answer 4

Start by setting the reasons variable to an empty array in the constructor.

let reasons = [];

Answer 5

Answer №3

translate.get functions by accepting an array, allowing you to retrieve all translations at once:

this.translate.get(this.keysList).subscribe((response) => {
  this.translations = response;
});

Please take note that if you have recently adopted ngx-translate, it may not receive future updates: https://github.com/ngx-translate/core/issues/783

Answer 6

translate.get functions by accepting an array, allowing you to retrieve all translations at once:

this.translate.get(this.keysList).subscribe((response) => {
  this.translations = response;
});

Please take note that if you have recently adopted ngx-translate, it may not receive future updates: https://github.com/ngx-translate/core/issues/783

Typescript error: Trying to use the `push` method on an undefined property

Answer №1

Answer №2

Answer №3

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