I am unable to invoke this function: TypeError: this.fetchData is not a function

Question

I am unable to invoke this function: TypeError: this.fetchData is not a function

Whenever I try to execute this.fetchData();, I encounter the error "TypeError: this.fetchData is not a function". Initially, I suspected that the context of 'this' was lost so I attempted using bind and arrow functions without success. How can I troubleshoot this issue?

class ShowResults extends Component {
    getData() {
        return setTimeout(function() {
            this.fetchData();
          }, 2000); //I tried using .bind(this) but it didn't work
        }
      }

      async fetchData() {
        //code
      }
}

javascript typescript

Answer 1

Answer №1

In this example, I have demonstrated how to bind a function using the constructor or onclick event.

  constructor(){
    super();
    this.getData = this.getData.bind(this);
  }

  getData() {
    return setTimeout(() => {
      this.fetchData();
    }, 0) //attempted to use bind but it didn't work--> .bind(this);
  };


  async fetchData() {
    console.log('Function executed successfully');
  }

Alternatively, you can also bind the function using the onClick event in JSX:

<header className="App-header" onClick={this.getData.bind(this)}></header>

Answer 2

In this example, I have demonstrated how to bind a function using the constructor or onclick event.

  constructor(){
    super();
    this.getData = this.getData.bind(this);
  }

  getData() {
    return setTimeout(() => {
      this.fetchData();
    }, 0) //attempted to use bind but it didn't work--> .bind(this);
  };


  async fetchData() {
    console.log('Function executed successfully');
  }

Alternatively, you can also bind the function using the onClick event in JSX:

<header className="App-header" onClick={this.getData.bind(this)}></header>

Answer 3

Answer №2

Based on your explanation, it appears that using .bind(this) is necessary due to the scope differences within the setTimeout function. If possible, could you provide additional code samples for further clarification as there seems to be an issue with the number of brackets in your code.

Answer 4

Based on your explanation, it appears that using .bind(this) is necessary due to the scope differences within the setTimeout function. If possible, could you provide additional code samples for further clarification as there seems to be an issue with the number of brackets in your code.

Answer 5

Answer №3

Another way to execute the method is by using the following code:

<header className="App-header" onClick={() => this.getData()}></header>

No need for manual binding. It automatically handles it.

Answer 6

Another way to execute the method is by using the following code:

<header className="App-header" onClick={() => this.getData()}></header>

No need for manual binding. It automatically handles it.

I am unable to invoke this function: TypeError: this.fetchData is not a function

Answer №1

Answer №2

Answer №3

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