How to validate javascript content in angular

Question

In my form, I have a text area. The textarea has to allow only javascript content. I have to validate the text area content, to check if it is javascript or not. How to check if the Text area contains data that is only valid javascript content?

I have a form , which allows choosing a file of type js and allows to write jscode in textarea,how can i validate written jscode in textarea? — Mariyam
– Mariyam, Commented May 28, 2019 at 4:37
If you want to validate the code of textarea you can do that by embedding eslint as a script. See eslint.org/docs/developer-guide/nodejs-api for more info. — Deepak Dixit
– Deepak Dixit, Commented May 28, 2019 at 4:46

Robby Cornelissen · Accepted Answer · 2019-05-28 05:07:43Z

1

Use a JavaScript parser like acorn and check whether you can correctly parse the textarea contents.

The snippet below uses acorn to try and parse the contents of two textareas, one containing valid JavaScript, and one just containing plain text.

function validateJs(textareaId) {
  const textarea = document.getElementById(textareaId);
  
  try {
    acorn.Parser.parse(textarea.value);
  } catch(e) {
    textarea.style.backgroundColor = 'red';
    return false;
  }
  
  textarea.style.backgroundColor = 'green';
  return true;
}

validateJs('good');
validateJs('bad');

<script src="https://cdnjs.cloudflare.com/ajax/libs/acorn/6.1.1/acorn.js"></script>

<textarea id="good" rows="4" cols="25">
function add(a, b) {
  return a + b;
}
</textarea>

<textarea id="bad" rows="4" cols="25">
Hello world!
</textarea>

edited May 28, 2019 at 5:07

answered May 28, 2019 at 4:50

Robby Cornelissen

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2 Comments

Mariyam Over a year ago

Used acorn.Parser.parse(textarea.value) and installed acron using npm i acron, but it shows error

Robby Cornelissen Over a year ago

Usage as a module is different. Refer to the source code/documentation on the GitHub page.

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