The variable "randomString" has not been declared within the HTMLInputElement.onclick function in Types

I need a function that can generate a random string or number for me.

Initially, my function in TypeScript looked like this:

  randomString() {
    let chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
    let string_length = 8;
    let randomstring = '';
    for (let i = 0; i < string_length; i++) {
      let rnum = Math.floor(Math.random() * chars.length);
      randomstring += chars.substring(rnum, rnum + 1);
    }
  }

HTML code:

    <form [formGroup]="addProductForm">
          <div class="input-field col s12">
                <input formControlName="Line_num" type="button" value="Create Random String" onClick="randomString();">  
  <input type="text" name="Line_num" value="">    
            </div>
    <form>

Upon clicking the button, I encountered this error: Uncaught ReferenceError: randomString is not defined at TMLInputElement.onclick

To fix this issue, I made the following changes:

this.addProductForm = this.fb.group({
    'Line_num': new FormControl(this.randomString(), Validators.required),
    });

In the modified function:

   randomString() { 
  return Math
    .random() // Create a random number
    .toString(36) // Convert it to string (26 letters + 10 numbers)
    .split('') // Creates an array of those letters
    .slice(-8) // Take the last height ones
    .join(''); // Join them back to create a string
}

Updated HTML code:

 <form [formGroup]="addProductForm">
    <div class="input-field col s12">
        <input type="text" formControlName="Line_num" name="Line_num">
</div>
</form>

By implementing these changes, the problem was successfully resolved.

Answer №1

Looking for a more straightforward method to generate random strings?

function generateRandomString() { 
  return Math
    .random() // Generates a random number
    .toString(36) // Converts it to a string (26 letters + 10 numbers)
    .split('') // Creates an array of those characters
    .slice(-8) // Takes the last eight characters
    .join(''); // Joins them back together into a string
}

This code snippet is easier to understand and should solve your problem.

For your specific use case:

this.addProductForm = this.fb.group({
  'Line_num': new FormControl(generateRandomString(), Validators.required)
});

Incorporate this in your HTML form:

<form [formGroup]="addProductForm">
  <input type="text" formControlName="Line_num" name="Line_num">
</form>

Answer №2

If you want to show your data in

<input type="text" name="Line_num" value="">

using JavaScript, one approach is to assign a unique ID to the input field like this

<input id="uniqueInputField" type="text" name="Line_num" value="">

then after the randomString function, you can simply set the value by using

document.getElementById("uniqueInputField").value = randomstring;

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