javascript - 使用 javascript 从数组中设置类的背景图像失败

Question

我有四个盒子我从数组项目中选择了 4 个项目

我已将随机选择的物品放在 4 个盒子内。

i want the image corresponding to the random index from array items to be backgroundImage of each box, ie if 2 is in the first box then URL corresponding to 2 should be the background image of the first box

因为我使用：

boxtags[index].style.backgroundImage = 'url(' + item[0].url + ')'; 

内右值（）；

but when applying the above code the boxes are not filled with values.

代码的错误在哪里？如何纠正它？

var items = [{
    label: '1',
    url: 'https://via.placeholder.com/75x75?text=1'
  },
  {
    label: '2',
    url: 'https://via.placeholder.com/75x75?text=2'
  },
  {
    label: '3',
    url: 'https://via.placeholder.com/75x75?text=3'
  },
  {
    label: '4',
    url: 'https://via.placeholder.com/75x75?text=4'
  },
  {
    label: '5',
    url: 'https://via.placeholder.com/75x75?text=5'
  },
  {
    label: '6',
    url: 'https://via.placeholder.com/75x75?text=6'
  },
  {
    label: '7',
    url: 'https://via.placeholder.com/75x75?text=7'
  },
  {
    label: '8',
    url: 'https://via.placeholder.com/75x75?text=8'
  },
  {
    label: '9',
    url: 'https://via.placeholder.com/75x75?text=9'
  },
  {
    label: '10',
    url: 'https://via.placeholder.com/75x75?text=10'
  }
];

var tempimages = [];
var array2 = [];
array2 = items.slice();

var backimgcount = 1;
var len = array2.length;

var item;
var displaycounter = 0;




var images = ['https://picsum.photos/200/300', 'https://picsum.photos/g/200/300'];
var index = 0;

function buildImage() {
  document.getElementById('content').style.backgroundImage = 'url(images/' + images[index] + ')';
}

function changeImage() {
  index++;
  if (index >= images.length) index = 0;
  document.getElementById('content').style.backgroundImage = 'url(images/' + images[index] + ')';
}


function rvalue() {


  elements = document.getElementsByClassName("box");

  elements = document.getElementsByClassName("box");

  for (var i = 0; i < elements.length; i++) {
    elements[i].style.backgroundColor = "#ff66ff";
    //elements[i].borderRadius = "2px";
    elements[i].style.border = "2px solid  #e3a89e ";
    //object.style.borderRadius = "1-4 length|% / 1-4 length|%|initial|inherit"

  }


  ptags = document.querySelectorAll('[name="values"]');
  boxtags = document.getElementsByClassName("box");


  for (var index = 0; index < 4; index++) {
    randomIndex = Math.floor(Math.random() * array2.length)

    item = array2[randomIndex];

    ptags[index].style.visibility = "visible";
    ptags[index].textContent = item.label;
    //boxtags[index].style.backgroundImage = 'url(' + item[0].url + ')'; 
    tempimages.push({
      data: item,
      index: randomIndex
    });

    ptags[index].dataset.itemIndex = randomIndex;

  }

  var tlen = tempimages.length;


}


function displayAllImages() {
  if (tempimages.length == 0) {

    rvalue();
  }
  //tempimages = tempimages.concat(tempimages.splice(0,2));
  //item = tempimages.splice(0, 1);

  function shuffle(array) {
    var currentIndex = array.length,
      temporaryValue, randomIndex;

    // While there remain elements to shuffle...
    while (0 !== currentIndex) {

      // Pick a remaining element...
      randomIndex = Math.floor(Math.random() * currentIndex);
      currentIndex -= 1;

      // And swap it with the current element.
      temporaryValue = array[currentIndex];
      array[currentIndex] = array[randomIndex];
      array[randomIndex] = temporaryValue;
    }

    return array;
  }


  var arr = tempimages;
  arr = shuffle(arr);

  item = arr.shift();
  image = document.getElementById('slide');
  image.src = item.data.url;
  image.dataset.itemIndex = item.index;


};

$(function() {

  displayAllImages();

});

function allowDrop(ev) {
  ev.preventDefault();
}

function drag(ev) {
  ev.dataTransfer.setData("Text", ev.target.id).classList.add('dashed');
}

function drop(ev) {

  ev.preventDefault();
  var data = ev.dataTransfer.getData("Text");
  var el = document.getElementById(data);


  var x = document.getElementById("slide").dataset.itemIndex;
  var y = ev.target.dataset.itemIndex;



  if (x == y) {
    //el.parentNode.removeChild; 

    ev.currentTarget.style.backgroundColor = 'initial';
    ev.currentTarget.style.border = 'initial';

    var pParagraph = ev.currentTarget.firstElementChild;
    //ev.currentTarget.removeChild(pParagraph);
    pParagraph.style.visibility = "hidden";

    item = this.item;
    var arrayvalue = item.dataindex;
    array2.splice(arrayvalue, 1);


    //alert("sucessfull");
    if (tempimages.length == 0) {
      rvalue();
      hiddenimage();
      //changeImage();
      changeImage();
    }
    displayAllImages();
  } else {
    playAudio2();
    alert("WRONG TIME PLACED");
  }

}

body {
  overflow: hidden;
}

.box {
  width: calc(33.3% - 4px);
  display: inline-block;
  border-radius: 5px;
  border: 2px solid #333;
  border: #000 border-color: #e6e600;
  margin: -2px;
  border-radius: 0%;
  background-color: #99ffff;
}

.box {
  height: 15vh;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.box002 {
  position: absolute;
  top: 27.3vh;
  left: 72.98vw;
  cursor: pointer;
}

.box002 img {
  width: 14.0vw;
  height: 23.0vh;
  border-radius: 50%;
}

.reset {
  position: absolute;
  top: 87.8vh;
  left: 73.3vw;
  cursor: pointer;
}

.reset img {
  width: 5.3vw;
  height: 11.1vh;
  border-radius: 50%;
}

.quit {
  position: absolute;
  top: 88.3vh;
  left: 84.3vw;
  cursor: pointer;
}

.quit img {
  width: 4.3vw;
  height: 9.5vh;
  border-radius: 50%;
}

#timer {
  font-family: 'Sigmar One', cursive;
  margin-top: -20%;
  margin-left: 120%;
}

#heading {
  font-family: 'Sigmar One', cursive;
  color: #F534BB;
}

#container {
  white-space: nowrap;
  border: px solid #CC0000;
}

.containerr {
  border: px solid #FF3399;
}

.pic {
  background-size: 100% 100%;
}

.container2 {
  width: 35.1vw;
  position: fixed;
  top: 43.5vh;
  left: 13.5vw;
}

.box p {
  font-size: calc(2vw + 10px);
}

p {
  font: "Courier New", Courier, monospace;
  font-size: 30px;
  color: rgba(0, 0, 0, 0.6);
  text-shadow: 2px 8px 6px rgba(0, 0, 0, 0.2), 0px -5px 35px rgba(255, 255, 255, 0.3);
  color: #005ce6;
  text-align: center;
}

.text {
  padding: 20px;
  margin: 7 px;
  margin-top: 10px;
  color: white;
  font-weight: bold;
  text-align: center;
}

body {
  background-size: 100vw 100vh;
}

.next {
  margin-right: 50%;
  margin-left: 50%;
  margin-bottom: 10%;
  float: right;
}

ul {
  -moz-border-radius: 50%;
  -webkit-border-radius: 50%;
}

.reset img:hover {
  opacity: 1
}

#hiddenimagewas {
  transform-origin: 50% 50%;
  font-size: 50px;
  font-family: 'Sigmar One', cursive;
  cursor: pointer;
  z-index: 2;
  text-align: center;
  width: 100%;
  position: absolute;
  top: 8.5vh;
  left: 0.3vw;
}

.hiddenimage {
  position: absolute;
  top: 15.3vh;
  left: 10vw;
  cursor: pointer;
}

.hiddenimage img {
  width: 35.3vw;
  height: 45.5vh;
  border-radius: 15%;
}

#timetaken2 {
  transform-origin: 50% 50%;
  font-size: 50px;
  font-family: 'Sigmar One', cursive;
  cursor: pointer;
  z-index: 2;
  text-align: center;
  width: 100%;
  position: absolute;
  top: 60.5vh;
  left: -12.8vw;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="congrats">

  <!----<h1 style="color:#FC6B67; font-size:24px;" id="hiddenimagewas">Hidden image was</h1>------>

</div>
</div>

<div class="container2">
  <div class="containerr">
    <div class="pic" id="content">
      <div id="container">

        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="10">
          <p name="values"></p>
        </div>
        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="11">
          <p name="values"></p>
        </div>
        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="12">
          <p name="values"></p>
        </div>
        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="13">
          <p name="values"></p>
        </div>
      </div>
    </div>
  </div>
</div>

<div class="box002" draggable="true" ondragstart="drag(event)" id="2">
  <img src="" draggable="true" id="slide" border="rounded" />
</div>

标签： javascripthtmlcss

Answer 1

主要问题来自于url从文字对象中获取的方式item。

item[0].url当item变量不是数组而是对象文字时，您将通过索引获取 url，因此您必须通过key直接使用item.url来获取值，例如：

boxtags[index].style.backgroundImage = 'url(' + item.url + ')';

var items = [{
    label: '1',
    url: 'https://via.placeholder.com/75x75?text=1'
  },
  {
    label: '2',
    url: 'https://via.placeholder.com/75x75?text=2'
  },
  {
    label: '3',
    url: 'https://via.placeholder.com/75x75?text=3'
  },
  {
    label: '4',
    url: 'https://via.placeholder.com/75x75?text=4'
  },
  {
    label: '5',
    url: 'https://via.placeholder.com/75x75?text=5'
  },
  {
    label: '6',
    url: 'https://via.placeholder.com/75x75?text=6'
  },
  {
    label: '7',
    url: 'https://via.placeholder.com/75x75?text=7'
  },
  {
    label: '8',
    url: 'https://via.placeholder.com/75x75?text=8'
  },
  {
    label: '9',
    url: 'https://via.placeholder.com/75x75?text=9'
  },
  {
    label: '10',
    url: 'https://via.placeholder.com/75x75?text=10'
  }
];

var tempimages = [];
var array2 = [];
array2 = items.slice();

var backimgcount = 1;
var len = array2.length;

var item;
var displaycounter = 0;




var images = ['https://picsum.photos/200/300', 'https://picsum.photos/g/200/300'];
var index = 0;

function buildImage() {
  document.getElementById('content').style.backgroundImage = 'url(images/' + images[index] + ')';
}

function changeImage() {
  index++;
  if (index >= images.length) index = 0;
  document.getElementById('content').style.backgroundImage = 'url(images/' + images[index] + ')';
}


function rvalue() {


  elements = document.getElementsByClassName("box");

  elements = document.getElementsByClassName("box");

  for (var i = 0; i < elements.length; i++) {
    elements[i].style.backgroundColor = "#ff66ff";
    //elements[i].borderRadius = "2px";
    elements[i].style.border = "2px solid  #e3a89e ";
    //object.style.borderRadius = "1-4 length|% / 1-4 length|%|initial|inherit"

  }


  ptags = document.querySelectorAll('[name="values"]');
  boxtags = document.getElementsByClassName("box");


  for (var index = 0; index < 4; index++) {
    randomIndex = Math.floor(Math.random() * array2.length)

    item = array2[randomIndex];

    ptags[index].style.visibility = "visible";
    ptags[index].textContent = item.label;

    boxtags[index].style.backgroundImage = 'url(' + item.url + ')';

    tempimages.push({
      data: item,
      index: randomIndex
    });

    ptags[index].dataset.itemIndex = randomIndex;

  }

  var tlen = tempimages.length;


}


function displayAllImages() {
  if (tempimages.length == 0) {

    rvalue();
  }
  //tempimages = tempimages.concat(tempimages.splice(0,2));
  //item = tempimages.splice(0, 1);

  function shuffle(array) {
    var currentIndex = array.length,
      temporaryValue, randomIndex;

    // While there remain elements to shuffle...
    while (0 !== currentIndex) {

      // Pick a remaining element...
      randomIndex = Math.floor(Math.random() * currentIndex);
      currentIndex -= 1;

      // And swap it with the current element.
      temporaryValue = array[currentIndex];
      array[currentIndex] = array[randomIndex];
      array[randomIndex] = temporaryValue;
    }

    return array;
  }


  var arr = tempimages;
  arr = shuffle(arr);

  item = arr.shift();
  image = document.getElementById('slide');
  image.src = item.data.url;
  image.dataset.itemIndex = item.index;


};

$(function() {

  displayAllImages();

});

function allowDrop(ev) {
  ev.preventDefault();
}

function drag(ev) {
  ev.dataTransfer.setData("Text", ev.target.id).classList.add('dashed');
}

function drop(ev) {

  ev.preventDefault();
  var data = ev.dataTransfer.getData("Text");
  var el = document.getElementById(data);


  var x = document.getElementById("slide").dataset.itemIndex;
  var y = ev.target.dataset.itemIndex;



  if (x == y) {
    //el.parentNode.removeChild; 

    ev.currentTarget.style.backgroundColor = 'initial';
    ev.currentTarget.style.border = 'initial';

    var pParagraph = ev.currentTarget.firstElementChild;
    //ev.currentTarget.removeChild(pParagraph);
    pParagraph.style.visibility = "hidden";

    item = this.item;
    var arrayvalue = item.dataindex;
    array2.splice(arrayvalue, 1);


    //alert("sucessfull");
    if (tempimages.length == 0) {
      rvalue();
      hiddenimage();
      //changeImage();
      changeImage();
    }
    displayAllImages();
  } else {
    playAudio2();
    alert("WRONG TIME PLACED");
  }

}

body {
  overflow: hidden;
}

.box {
  width: calc(33.3% - 4px);
  display: inline-block;
  border-radius: 5px;
  border: 2px solid #333;
  border: #000 border-color: #e6e600;
  margin: -2px;
  border-radius: 0%;
  background-color: #99ffff;
}

.box {
  height: 15vh;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
}

.box002 {
  position: absolute;
  top: 27.3vh;
  left: 72.98vw;
  cursor: pointer;
}

.box002 img {
  width: 14.0vw;
  height: 23.0vh;
  border-radius: 50%;
}

.reset {
  position: absolute;
  top: 87.8vh;
  left: 73.3vw;
  cursor: pointer;
}

.reset img {
  width: 5.3vw;
  height: 11.1vh;
  border-radius: 50%;
}

.quit {
  position: absolute;
  top: 88.3vh;
  left: 84.3vw;
  cursor: pointer;
}

.quit img {
  width: 4.3vw;
  height: 9.5vh;
  border-radius: 50%;
}

#timer {
  font-family: 'Sigmar One', cursive;
  margin-top: -20%;
  margin-left: 120%;
}

#heading {
  font-family: 'Sigmar One', cursive;
  color: #F534BB;
}

#container {
  white-space: nowrap;
  border: px solid #CC0000;
}

.containerr {
  border: px solid #FF3399;
}

.pic {
  background-size: 100% 100%;
}

.container2 {
  width: 35.1vw;
  position: fixed;
  top: 43.5vh;
  left: 13.5vw;
}

.box p {
  font-size: calc(2vw + 10px);
}

p {
  font: "Courier New", Courier, monospace;
  font-size: 30px;
  color: rgba(0, 0, 0, 0.6);
  text-shadow: 2px 8px 6px rgba(0, 0, 0, 0.2), 0px -5px 35px rgba(255, 255, 255, 0.3);
  color: #005ce6;
  text-align: center;
}

.text {
  padding: 20px;
  margin: 7 px;
  margin-top: 10px;
  color: white;
  font-weight: bold;
  text-align: center;
}

body {
  background-size: 100vw 100vh;
}

.next {
  margin-right: 50%;
  margin-left: 50%;
  margin-bottom: 10%;
  float: right;
}

ul {
  -moz-border-radius: 50%;
  -webkit-border-radius: 50%;
}

.reset img:hover {
  opacity: 1
}

#hiddenimagewas {
  transform-origin: 50% 50%;
  font-size: 50px;
  font-family: 'Sigmar One', cursive;
  cursor: pointer;
  z-index: 2;
  text-align: center;
  width: 100%;
  position: absolute;
  top: 8.5vh;
  left: 0.3vw;
}

.hiddenimage {
  position: absolute;
  top: 15.3vh;
  left: 10vw;
  cursor: pointer;
}

.hiddenimage img {
  width: 35.3vw;
  height: 45.5vh;
  border-radius: 15%;
}

#timetaken2 {
  transform-origin: 50% 50%;
  font-size: 50px;
  font-family: 'Sigmar One', cursive;
  cursor: pointer;
  z-index: 2;
  text-align: center;
  width: 100%;
  position: absolute;
  top: 60.5vh;
  left: -12.8vw;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="congrats">

  <!----<h1 style="color:#FC6B67; font-size:24px;" id="hiddenimagewas">Hidden image was</h1>------>

</div>
</div>

<div class="container2">
  <div class="containerr">
    <div class="pic" id="content">
      <div id="container">

        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="10">
          <p name="values"></p>
        </div>
        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="11">
          <p name="values"></p>
        </div>
        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="12">
          <p name="values"></p>
        </div>
        <div class="box" ondrop="drop(event)" ondragover="allowDrop(event)" id="13">
          <p name="values"></p>
        </div>
      </div>
    </div>
  </div>
</div>

<div class="box002" draggable="true" ondragstart="drag(event)" id="2">
  <img src="" draggable="true" id="slide" border="rounded" />
</div>