javascript - 如何传递解析值

Question

使用这个Promise有什么问题吗？

const count_elems = function(c){
  const elems = c.getElementsByTagName('p');
  console.log(elems.length);
};

const handler = function(){
    return new Promise(function (resolve, reject) {
     const cont = document.getElementById('cont');
     const p = document.createElement('p');
     for (let i=100000; i--;){
        cont.appendChild(p.cloneNode());
     }
     return resolve(cont);
  })
}

const test = function(){
  handler()
    .then(count_elems(c))
    .catch(function(e){console.log(e)});
};

document.getElementById('but')
  .addEventListener('click', test);

 <div id="cont"></div>
  <button id="but">click me</button>

Answer 1

在then函数中获取c，然后传入count_elems函数。另外，请删除 resolve 之前的 return，您不需要这样做。

.then(c => count_elems(c)) 或仅 .then(count_elems) 而无需函数调用。

const count_elems = function(c){
   const elems = c.getElementsByTagName('p');
   console.log(elems.length);
};

const handler = function() {

   return new Promise(function (resolve, reject) {
      const cont = document.getElementById('cont');
      const p = document.createElement('p');
      
      for (let i=100000; i--;){
         cont.appendChild(p.cloneNode());
      }
     
      resolve(cont);
  });
  
}

const test = function() {
   handler().then(c => count_elems(c))
            .catch(e => console.log(e));
};

document.getElementById('but')
        .addEventListener('click', test);

<div id="cont"></div>
<button id="but">click me</button>