JavaScript .then 方法

Question

单击此代码中的按钮后，我想要

consloe.log("Hello")

打印。

async function remove_tag() {
  let pr = new Promise(function(resolve, reject) {
    function done() {
      let btn = document.getElementById("btn");
      function button() {
        let tag = document.getElementById("main_1");
        tag.remove();
      }
      btn.addEventListener("click", button)
      let msg = "done";
      return msg;
    }
    resolve(done());
  })
  let wait_promise = await pr;
  return wait_promise;
}

remove_tag()
  .then((value) => {
    console.log("hello")
  });

我尝试了很多时间，但在我点击按钮之前打印了“你好”。

Answer 1

现在你在你的

resolve

定义中立即调用

Promise

，导致

Promise

立即解决。您需要在

button

函数中调用它，以便它在单击时运行。

async function remove_tag(){
    let pr = new Promise(function(resolve, reject) {
        let btn = document.getElementById("btn");
        function button(){
            let tag = document.getElementById("main_1");
            tag.remove();
            let msg = "done";
            resolve(msg);
        }
        btn.addEventListener("click", button);
    })
    let wait_promise = await pr;
    return wait_promise;
}

remove_tag()
.then((value)=>{
    console.log("hello");
})

Answer 2

async function remove_tag() {
  let pr = new Promise(function(resolve, reject) {
    function done() {
      let btn = document.getElementById("btn");
      function button() {
        let tag = document.getElementById("main_1");
        tag.remove();
        console.log("hello"); // move console.log here
      }
      btn.addEventListener("click", button);
      let msg = "done";
      return msg;
    }
    resolve(done());
  });
  let wait_promise = await pr;
  return wait_promise;
}

remove_tag();

Answer 3

async function remove_tag() {
  let pr = new Promise(function(resolve, reject) {
    function done() {
      let btn = document.getElementById("btn");
      function button() {
        let tag = document.getElementById("main_1");
        tag.remove();
        resolve(); // resolve the promise after button click
      }
      btn.addEventListener("click", button);
    }
    done();
  })
  await pr; // wait for the promise to be resolved after button click
}

remove_tag()
  .then(() => {
    console.log("hello");
  });