我用这个:

jQuery插件

(function($){
  $.fn.getFormData = function(){
    var data = {};
    var dataArray = $(this).serializeArray();
    for(var i=0;i<dataArray.length;i++){
      data[dataArray[i].name] = dataArray[i].value;
    }
    return data;
  }
})(jQuery);

HTML表单

<form id='myform'>
  <input name='myVar1' />
  <input name='myVar2' />
</form>

获取数据

var myData = $("#myForm").getFormData();

这里有一个非常简单和简短的解决方案，甚至不需要Jquery。

var formElements=document.getElementById("myForm").elements;    
var postData={};
for (var i=0; i<formElements.length; i++)
    if (formElements[i].type!="submit")//we dont want to include the submit-buttom
        postData[formElements[i].name]=formElements[i].value;

现在是2019年，有一个更好的方法:

const form = document.querySelector('form');
const data = new URLSearchParams(new FormData(form).entries());

或者如果你想要一个普通的对象

const form = document.querySelector('form');
const data = Object.fromEntries(new FormData(form).entries());

尽管请注意，这将不适用于重复的键，如您从多选和重复的复选框具有相同的名称。

$("#form input, #form select, #form textarea").each(function() {
 data[theFieldName] = theFieldValue;
});

除此之外，你可能想看看serialize();

这是一个很好的香草JS函数，我写来提取表单数据作为一个对象。它还具有向对象中插入附加内容和清除表单输入字段的选项。

const extractFormData = ({ form, clear, add }) => {
  return [].slice.call(form.children).filter(node => node.nodeName === 'INPUT')
  .reduce((formData, input) => {
    const value = input.value
    if (clear) { input.value = '' }
    return {
      ...formData,
      [input.name]: value
    }
  }, add)
}

下面是一个使用post请求的例子:

submitGrudge(e) {
  e.preventDefault()

  const form = e.target
  const add = { id: Date.now(), forgiven: false }
  const grudge = extractFormData({ form, add, clear: true })

  // grudge = {
  //  "name": "Example name",
  //  "offense": "Example string",
  //  "date": "2017-02-16",
  //  "id": 1487877281983,
  //  "forgiven": false
  // }

  fetch('http://localhost:3001/api/grudge', {
    method: 'post',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(grudge)
  })
    .then(response => response.json())
    .then(grudges => this.setState({ grudges }))
    .catch(err => console.log('error: ', err))
}

document.querySelector('form').addEventListener('submit', (e) => {
  const formData = new FormData(e.target);
  // Now you can use formData.get('foo'), for example.
  // Don't forget e.preventDefault() if you want to stop normal form .submission
});

这是一个吹毛求疵的答案，但让我解释为什么这是一个更好的解决方案:

We're properly handling a form submit rather than a button press. Some people like to push enter on fields. Some people use alternative input devices such as speech input or other accessibility devices. Handle the form submit and you correctly solve it for everyone. We're digging into the form data for the actual form that was submitted. If you change your form selector later, you don't have to change the selectors for all the fields. Furthermore, you might have several forms with the same input names. No need to disambiguate with excessive IDs and what not, just track the inputs based on the form that was submitted. This also enables you to use a single event handler for multiple forms if that is appropriate for your situation. The FormData interface is fairly new, but is well supported by browsers. It's a great way to build that data collection to get the real values of what's in the form. Without it, you're going to have to loop through all the elements (such as with form.elements) and figure out what's checked, what isn't, what the values are, etc. Totally possible if you need old browser support, but the FormData interface is simpler. I'm using ES6 here... not a requirement by any means, so change it back to be ES5 compatible if you need old browser support.