原生JS实现获取Form表单数据的方法

//获取指定form中的所有的<input>对象 
function getElements(formId) { 
  var form = document.getElementById(formId); 
  var elements = new Array(); 
  var tagElements = form.getElementsByTagName('input'); 
  for (var j = 0; j < tagElements.length; j++){ 
    elements.push(tagElements[j]); 
  } 
  var tagElements = form.getElementsByTagName('select'); 
  for (var j = 0; j < tagElements.length; j++){ 
    elements.push(tagElements[j]); 
  } 
  var tagElements = form.getElementsByTagName('textarea'); 
  for (var j = 0; j < tagElements.length; j++){ 
    elements.push(tagElements[j]); 
  }
  return elements; 
} 
//组合URL 
function serializeElement(element) { 
  var method = element.tagName.toLowerCase(); 
  var parameter; 
  if(method == 'select'){
    parameter = [element.name, element.value]; 
  }
  switch (element.type.toLowerCase()) { 
    case 'submit': 
    case 'hidden': 
    case 'password': 
    case 'text':
    case 'date':
    case 'textarea': 
       parameter = [element.name, element.value];
       break;
    case 'checkbox': 
    case 'radio': 
      if (element.checked){
        parameter = [element.name, element.value]; 
      }
      break;    
  } 
  if (parameter) { 
    var key = encodeURIComponent(parameter[0]); 
    if (key.length == 0) 
      return; 
    if (parameter[1].constructor != Array) 
      parameter[1] = [parameter[1]]; 
    var values = parameter[1]; 
    var results = []; 
    for (var i = 0; i < values.length; i++) { 
      results.push(key + '=' + encodeURIComponent(values[i])); 
    } 
    return results.join('&'); 
  } 
} 
//调用方法  
function serializeForm(formId) { 
  var elements = getElements(formId); 
  var queryComponents = new Array(); 
  for (var i = 0; i < elements.length; i++) { 
    var queryComponent = serializeElement(elements[i]); 
    if (queryComponent) {
      queryComponents.push(queryComponent); 
    } 
  } 
  return queryComponents.join('&'); 
} 

id=1&title=%E6%B4%BB%E5%8A%A8&time=2017-07-10&status=1&importance=0&desc=%E5%9C%A8%E4%BA%8C%E6%A5%BC%E5%8A%9E%E5%85%AC%E5%AE%A4%E5%BC%80%E4%BC%9A%EF%BC%8C%E4%B8%80%E7%82%B9%E9%92%9F