Send form data to Javascript on submit

问题:

Ok I feel like this should be really simple; so either I've completely missed the point of the questions on here and other websites I've read or it hasn't been asked in the same context....

I have a REALLY simple form element (below)

<form>
  <input type="text" id="searchTerm" />
  <input type="submit" value="Submit" id="submitButton" />
</form>

And essentially all I want to do, when the Submit button is clicked, is have the value entered into the text box passed to a JavaScript Function and console logged (for now).

This looks like it has been asked a million times but the questions I've read don't answer my question (I don't think).

Edit Thank you for all the responses; the biggest problem is I was trying to reference a function in an external Javascript file that was being called after the form element.

回答1:

Something like this?

document.getElementById('theform').onsubmit = function() { 
    console.log(document.getElementById('searchTerm').value);
    return false;
};

JSFiddle here: https://jsfiddle.net/km7rt62v/

It's important to return false; to prevent default behaviour at the end of your submit handler, as otherwise the form will post and reload the page.

As others have demonstrated, it is also possible to use the onsubmit html attribute of the form element, it's a personal preference, but I prefer a cleaner separation between JS and HTML.

Edit: Since I got accepted answer and the question is tagged with jQuery, here's the jQuery equivalent:

$('#theform').submit(function() { 
    console.log($('#searchTerm').val());
    return false;
});

回答2:

It is not necessary to add yet another getElementById() inside the submit form handler function. I am confused as to why this approach is so common. What would you do if you needed to fetch multiple dozens / all values of the form? Write dozens of element selectors?

I think the following is much cleaner:

Inputs can include a name attribute which eases their access:

  function submitForm(event) {
    alert(event.target.elements.searchTerm.value)
    return false;
  }

<form onsubmit="submitForm(event)">
  <input name="searchTerm"/>
  <button>Submit</button>
</form>

Even better,

function submitForm(that) {
  alert(that.searchTerm.value)
  return false;
}

<form onsubmit="submitForm(this)">
  <input name="searchTerm"/>
  <button>Submit</button>
</form>

In the handler itself, you can even access values directly:

<form onsubmit="alert(searchTerm); false">
  <input name="searchTerm"/>
  <button>Submit</button>
</form>

Even though I have no idea why the latest example works; Havent found any documentation regarding this yet; I opened a question here.

If you register the event handler via JS, the this (in non-lambda functions) already points to the form element, so you can also do

document.querySelector('#myForm').addEventListener('submit', function() {
  event.preventDefault()
  alert(this.elements.searchTerm.value)
});

<form id="myForm">
  <input name="searchTerm"/>
  <button>Submit</button>
</form>

If you want to get a key/value mapping (plain) object out of an HTML form, see this answer.

回答3:

This is a pure simple JavaScript. You could use jQuery as well.

function checkForm(){
  console.log(document.getElementById('searchTerm').value);
  return false;
}

<form onsubmit='return checkForm();'>
  <input type="text" id="searchTerm" />
  <input type="submit" value="Submit" id="submitButton" />
</form>

回答4:

there is an attribute you can use called onsubmit when you include an input with the type of submit in your form. Here is some documentation http://www.w3schools.com/tags/ev_onsubmit.asp.

The code would look something like this

<form onsubmit="submitForm()">
  <input type="text" id="searchTerm"/>
  <input type="submit" value="Submit" id="submitButton" />
</form>

<script>
  function submitForm() {
    let input = document.querySelector('#searchTerm');
    console.log(input.value);
    return false;
  }
</script>

回答5:

To have such a function in an external file, your best bet is to wire the submit event in an onload event:

window.onload=function() {
  document.getElementById("form1").onsubmit=function(e) {
    e=e?e:event;
    e.preventDefault(); // cancel the submit
    var val = document.getElementById("searchTerm").value;
    console.log(val);
  }  
}

<form id="form1">
  <input type="text" id="searchTerm" />
  <input type="submit" value="Submit" id="submitButton" />
</form>

jQuery version:

$(function() {
  $("#form1").on("submit",function(e) {
    e.preventDefault(); // cancel the submit
    var val = $("#searchTerm").val();
    console.log(val);
  }); 
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<form id="form1">
  <input type="text" id="searchTerm" />
  <input type="submit" value="Submit" id="submitButton" />
</form>

回答6:

You tagged this with jQuery, so here's a jQuery answer. What you need to use is the .submit() event handler.

$("form").submit(function(e) {
    console.log("form data: %o", $(this).find("#searchTerm").val());
    e.preventDefault();
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<form>
    <input type="text" id="searchTerm" />
    <input type="submit" value="Submit" id="submitButton" />
</form>

This code will attach a handler to the <form> onsubmit event:

回答7:

Submit form:

JS:

var searchForm= document.getElementById('searchForm');
var submitButton = document.getElementById('submitButton');

searchForm.onsubmit= function () {
  console.log(searchTerm.value);
};

HTML:

<form id="searchForm">
  <input type="text" id="searchTerm" />
  <input type="submit" value="Submit" id="submitButton" />
</form>

On click for button:

JS:

var searchTerm = document.getElementById('searchTerm');
var submitButton = document.getElementById('submitButton');

submitButton.onclick = function () {
  console.log(searchTerm.value);
};

HTML:

<form>
  <input type="text" id="searchTerm" />
  <input type="button" value="Submit" id="submitButton" />
</form>

See demo Here

回答8:

So the main issue was I had included the <script> element, linking to my external JavaScript file, at the bottom of my <body> element; meaning that at the time of the form being created it didn't know what Javascript Function I was talking about.

Thanks to all of those that helped, and this was the solution....

HTML

<head>
  <!-- jQuery library -->
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.0/jquery.min.js"></script>
  <!-- Custom JavaScript -->
  <script src="js/wiki.js"></script>
</head>
<body>
  <form id="theform" onsubmit="test(this.searchTerm.value)">
    <input type="text" id="searchTerm" />
    <input type="submit" value="Submit" id="submitButton" />
  </form>
</body>
</html>

JavaScript

$(document).ready(function() {

  test = function(value) {
      console.log(value);
    return false;
  };

});