When using the `Document.write()` method, an error is returned stating, "Uncaught TypeError: Cannot read property 'document' of null"

Question

When using the `Document.write()` method, an error is returned stating, "Uncaught TypeError: Cannot read property 'document' of null"

I am currently integrating Angular2 into a website as the front-end framework, and it will be displayed on another website using an iframe. When working with the HTTP post method, I am able to receive a JSON response.

Here is the API Post method that returns a JSON result.

After sending the post request from the front end, I extract the response and convert it into JSON format. Then, in my AppService class, I set a variable using a setter method. An issue arises when trying to dynamically generate HTML content in a new tab upon completion of the HTTP request using document.write().

This is the code snippet for the front-end Post request.

To address this problem, I considered two options: sending a window.postMessage() to the parent of the iframe to trigger the opening of a new tab, or embedding another iframe within the existing one. However, both solutions are suboptimal.

javascript angular http typescript

Answer 1

Answer №1

There is a possibility that the browser may block a pop-up window from appearing. In such cases, when window.open() fails to open the window, it will return null. As a result, you will need to adjust your script to account for this scenario.

Modern browsers have become adept at preventing pop-up windows by allowing scripts to open them only in direct response to user actions. This means that using window.open() right after an AJAX request might not work as expected. One solution is to open the window immediately upon user interaction, then proceed with the AJAX request and write the content to the window upon completion. Here's an example:

button.onClick = function() {
  var popUp = window.open();
  if (popUp) {
    doAjaxRequest().then(function(data) {
      popUp.document.write(data);
      popUp.document.close();
    });
  }
}

Answer 2

There is a possibility that the browser may block a pop-up window from appearing. In such cases, when window.open() fails to open the window, it will return null. As a result, you will need to adjust your script to account for this scenario.

Modern browsers have become adept at preventing pop-up windows by allowing scripts to open them only in direct response to user actions. This means that using window.open() right after an AJAX request might not work as expected. One solution is to open the window immediately upon user interaction, then proceed with the AJAX request and write the content to the window upon completion. Here's an example:

button.onClick = function() {
  var popUp = window.open();
  if (popUp) {
    doAjaxRequest().then(function(data) {
      popUp.document.write(data);
      popUp.document.close();
    });
  }
}

When using the `Document.write()` method, an error is returned stating, "Uncaught TypeError: Cannot read property 'document' of null"

Answer №1

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