遍历form表单里面的表单元素，取其value

form.elements 获取所有表单元素

form 表单

  <form action="http://localhost:1995/api/post" class="form" method="post">
    <input type="text" name="name" value="ajanuw">
    <input type="text" name="name" value="alone">
    <input type="text" name="name" value="xxx" disabled>
    <input type="text" value="bbb">
    <input type="password" name="pass" value="123">
    <button type="submit">p</button>
    <div>
      <p>单选框 性别</p>
      男：
      <input type="radio" name="sex" checked value="男"> 女：
      <input type="radio" name="sex" checked value="女">
    </div>
    <div>
      足球：
      <input type="checkbox" name="zuqiu" checked value="足球"> 篮球：
      <input type="checkbox" name="lanqiu" checked value="蓝球">
    </div>
    <p>
      <textarea name="wneben" id="" cols="30" rows="10">hello world</textarea>
    </p>
    <div>
      <select name="form-select" multiple class="asd">
        <option value="a" selected>aaa</option>
        <option value="b" selected>bbb</option>
        <option selected>
          hello
          <p>hello</p>
        </option>
      </select>
    </div>
    <fieldset name="group-from">
      <legend>健康信息</legend>
      身高：
      <input type="text" name="height" value="111" /> 体重：
      <input type="text" name="weight" value="222" />
    </fieldset>
  </form>

js 代码

 let l = console.log;    function qs(s) {
      return document.querySelector(s)
    }
    let toArray = Array.from;    let f = qs('.form')
    let body = {}
    scanDOM(f);    function scanDOM(box) {
      let eles = toArray(box.children)
      for (let ele of eles) {
        if (ele.children.length && ele.nodeName !== 'SELECT' && ele.nodeName !== 'FIELDSET') { // select元素没有必要递归，表单包也暂时不用遍历
          scanDOM(ele)
        } else {
          let nodeName = ele.nodeName.toLowerCase();
          let formElementp = (v) => v === 'input' || v === 'select' || v === 'textarea' || v === 'fieldset';
          if (formElementp(nodeName)) { // 确认元素是表单元素
            if (ele.disabled === true) continue; // 如果元素为禁用则跳过
            let k, v;
            k = ele.name;
            if (!k) continue; // 没有name的表单元素跳过
            if (ele.type === 'radio') { // 单选按钮时，需要判断是否为选中状态
              if (!ele.checked) continue;
              v = ele.value;
            } else if (ele.type === 'checkbox') {
              if (!ele.checked) continue;
              v = ele.value;
            } else {
              if (nodeName === 'select' && ele.multiple) {
                let vs = []; // 收集所有多选状态下的 selected的value，
                let options = toArray(ele.children);
                for (let o of options) {
                  vs.push(o.value)
                }
                v = vs;
              } else if (nodeName === 'fieldset') {
                scanDOM(ele)
              } else {
                v = ele.value;
              }
            }
            if(v === undefined) continue;
            let alive = k in body;
            if (alive) { // 已经存在相应的name
              let ov = body[k]
              if (Object.prototype.toString.call(body[k]) === '[object Array]') {
                body[k] = ov.concat(v)
              } else {
                body[k] = [ov, v]
              }
            } else {
              body[k] = v;
            }
          }        }
      }
    }
    l(body)