Javascript – Trigger autocomplete without submitting a form

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I am writing a very simple web app with three text inputs. The inputs are used to generate a result, but all the work is done in Javascript, so there is no need to submit a form. I'm trying to find a way to get the browser to store input values for autocomplete as it would if they were in a form that was submitted.

I have tried giving the inputs autocomplete="on" manually, but without a form to submit, the browser has no way of knowing when it should store the values, so this has no effect.

I have also tried wrapping the inputs in a form that has onSubmit="return false;", but preventing the form from actually submitting appears to also prevent the browser from storing its inputs' values.

It is of course possible to manually use localStorage or a cookie to persist inputs and then generate autocomplete hints from those, but I'm hoping to find a solution that taps into native browser behavior instead of duplicating it by hand.

Best Answer

Tested with Chrome, IE and Firefox:

<iframe id="remember" name="remember" class="hidden" src="/content/blank"></iframe>

<form target="remember" method="post" action="/content/blank">
  <fieldset>
    <label for="username">Username</label>
    <input type="text" name="username" id="username" value="">
    <label for="password">Password</label>
    <input type="password" name="password" id="password" value="">
  </fieldset>
  <button type="submit" class="hidden"></button>
</form>

In your Javascript trigger the submit, e.g. ~~$("form").submit();~~ $("#submit_button").click() (updated from comments)

You need to return an empty page at /content/blank for get & post (about:blank didn't work for me but YMMV).

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Firefox 30 ignores autocomplete="off" for passwords, opting to prompt the user instead whether the password should be stored on the client. Note the following commentary from May 5, 2014:

The password manager always prompts if it wants to save a password. Passwords are not saved without permission from the user.

We are the third browser to implement this change, after IE and Chrome.

According to the Mozilla Developer Network documentation, the Boolean form element attribute autocomplete prevents form data from being cached in older browsers.

<input type="text" name="foo" autocomplete="off" />

JavaScript post request like a form submit

Dynamically create `<input>`s in a form and submit it

/**
 * sends a request to the specified url from a form. this will change the window location.
 * @param {string} path the path to send the post request to
 * @param {object} params the parameters to add to the url
 * @param {string} [method=post] the method to use on the form
 */

function post(path, params, method='post') {

  // The rest of this code assumes you are not using a library.
  // It can be made less verbose if you use one.
  const form = document.createElement('form');
  form.method = method;
  form.action = path;

  for (const key in params) {
    if (params.hasOwnProperty(key)) {
      const hiddenField = document.createElement('input');
      hiddenField.type = 'hidden';
      hiddenField.name = key;
      hiddenField.value = params[key];

      form.appendChild(hiddenField);
    }
  }

  document.body.appendChild(form);
  form.submit();
}

Example:

post('/contact/', {name: 'Johnny Bravo'});

EDIT: Since this has gotten upvoted so much, I'm guessing people will be copy-pasting this a lot. So I added the hasOwnProperty check to fix any inadvertent bugs.

Best Answer

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JavaScript post request like a form submit

Dynamically create <input>s in a form and submit it

Related Topic

Dynamically create `<input>`s in a form and submit it