javascript - 如何使用 JavaScript 更改 CSS 显示属性？

Question

我无法更改 img 标签的显示属性。

我已将显示更改为内联或 block 。

function toggle_btn_img() {

  let btnId = document.getElementById("btn");
  let avatarId = document.getElementById("avatar");

  if (btnId.innerHTML === "Show!") {
    avatarId.style.display = "block";
    btnId.innerHTML = "Hide!";
  } else {
    avatarId.style.display = "none";
    btnId.innerHTML = "Show!";
  }
}

<div class="w3-display-container w3-card w3-col s4 w3-display-middle w3-light-gray" style="height: 30%;">
  <div class="w3-display-right w3-col s6 w3-display-container">
    <button id="btn" onclick="toggle_btn_img()" class="w3-btn w3-card w3-round w3-light-green w3-hover-green w3-text-white w3-text-hover-gray w3-display-middle w3-col s4">Show!</button>
  </div>
  <div class="w3-display-left w3-dispaly-container w3-col s6">
    <div id="avatar_container" class="w3-card w3-circle w3-display-middle w3-pale-blue" style="height: 150px; width: 150px;"><img id="avatar" src='http://placekitten.com/200/300' class="w3-hide w3-col s11 w3-display-middle" /></div>
  </div>
</div>

我希望图像显示和隐藏，但事实并非如此。 (我不能更改 html 或 css 文件!)

Answer 1

首先你必须通过CSS或JS隐藏它，否则第一次点击按钮将不会有任何效果。一旦你这样做了，你就会得到预期的结果:

let btnId = document.getElementById("btn");
let avatarId = document.getElementById("avatar");            
avatarId.style.display = "none";

function toggle_btn_img() {

    if (btnId.innerHTML === "Show!") {
        avatarId.style.display = "block";
        btnId.innerHTML = "Hide!";
    } else {
        avatarId.style.display = "none";
        btnId.innerHTML = "Show!";
    }   
}   

#avatar {
  display: none;
}

<div class="w3-display-container w3-card w3-col s4 w3-display-middle w3-light-gray" style="height: 30%;">
    <div class="w3-display-right w3-col s6 w3-display-container">
        <button id="btn" onclick="toggle_btn_img()" class="w3-btn w3-card w3-round w3-light-green w3-hover-green w3-text-white w3-text-hover-gray w3-display-middle w3-col s4">Show!</button>
    </div>
    <div class="w3-display-left w3-dispaly-container w3-col s6" >
        <div id="avatar_container" class="w3-card w3-circle w3-display-middle w3-pale-blue" style="height: 150px; width: 150px;"><img id="avatar" src='//placekitten.com/200/300' class="w3-hide w3-col s11 w3-display-middle"/></div>
    </div>
</div>