javascript - Src 属性更改后更新图像

Question

你们好，很棒的人们，

我试图在更改“src”属性后更新图像。我尝试在网址后附加日期戳，但这似乎不起作用。有人可以告诉我哪里出错了，或者只是建议一个更好的方法来完成这一切？

我已经包含了迄今为止的整个代码，因为我不确定问题出在哪里。恐怕我有点菜鸟。 “displayOut”函数中的前三行很可能是问题所在。预先感谢您的帮助。

var db = [{ // ROOMS
    rooms: [{ // Room 0 - North room
      description: "You awake to find yourself in a dank smelling old room, plaster and smashed glass litters the floor. To the North is a broken window, beyond which you can only see a thick grey mist. There is one door by which to exit, to the South.",
      roomImg: "images/room_0.jpg",
      exits: {
        north: false,
        south: 1,
        east: false,
        west: false,
        up: false,
        down: false
      },
      roomInvent: ["a Box of Matches", "a Glass Shard"]
    }, { // Room 1 - Corridor
      description: "You are in a short, dark corridor, a single tungsten bulb hangs stiffly from the ceiling. There is a light switch on the wall.",
      roomImg: "images/room_1.jpg",
      exits: {
        north: 0,
        south: 4,
        east: 3,
        west: false,
        up: 5,
        down: false
      },
      roomInvent: []
    }, { // Room 2 - West Room - Locked room
      description: "",
      roomImg: "images/room_2.jpg",
      exits: {
        north: false,
        south: false,
        east: false,
        west: false,
        up: false,
        down: false
      },
      roomInvent: []
    }, { // Room 3 - East room - Bedroom
      description: "You are in the Bedroom",
      roomImg: "images/room_3.jpg",
      exits: {
        north: false,
        south: false,
        east: false,
        west: 1,
        up: false,
        down: false
      },
      roomInvent: []
    }, { // Room 4 - South room - kitchen
      description: "You are in a small kitchen. There is an old log fire on the East wall, and a door leading outside to the South.",
      roomImg: "images/room_4.jpg",
      exits: {
        north: 1,
        south: false,
        east: false,
        west: false,
        up: false,
        down: false
      },
      roomInvent: []
    }, { // Room 5 - Attic
      description: "You are in the Attic.",
      roomImg: "images/room_5.jpg",
      exits: {
        north: false,
        south: false,
        east: false,
        west: false,
        up: false,
        down: 1
      },
      roomInvent: []
    }]
  }, // End Rooms
  { // ITEMS
    items: [{
      itemIndex: 0,
      name: "a Box of Matches",
      useWith: null,
      examine: "There is only a single match inside."
    }, {
      itemIndex: 1,
      name: "a Glass Shard",
      useWith: null,
      examine: "It looks sharp"
    }, {
      itemIndex: 2,
      name: "a Mallet",
      useWith: null,
      examine: "It is old and rusty, but otherwise uninteresting."
    }]
  }

]; //End db

var inventory = [];
var inputTextBox = document.getElementById("inputTextBox");
var diologueBox = document.getElementById("diologueBox");
var strOut = "";
var roomLoc = 0;



function displayOut() {
  // images
  let dt = new Date;
  document.getElementById("imgBox").setAttribute("src", db[0].rooms[roomLoc].roomImg + "?dt=" + dt.getTime());
  // Diologue box
  diologueBox.innerHTML = db[0].rooms[roomLoc].description +
    (function() { // Check if room has items in inventory, if so, list them.
      if (db[0].rooms[roomLoc].roomInvent != "") {
        return "<br><br> The room contains " +
          (function() {
            let items = "";
            for (let i = 0; i < db[0].rooms[roomLoc].roomInvent.length; i++) {
              items += db[0].rooms[roomLoc].roomInvent[i] + ", ";
            };
            items = items.slice(0, items.length - 2);
            return items;
          })();
      } else {
        return "<br><br> The room is empty ";
      };
    })();
};
// Function for changing room location
function navigateTo(direction) {
  if (db[0].rooms[roomLoc].exits[direction] === false) {
    outputBox.innerHTML = "You cannot go " + direction + " from here."
  } else {
    roomLoc = db[0].rooms[roomLoc].exits[direction];
    displayOut();
  }
}

inputTextBox.addEventListener("keypress", function(event) {
  let x = event.which || event.keyCode;
  if (x === 13) { // 13 is the Return key
    switch (inputTextBox.value.toLowerCase()) {
      //Diologue Navigation
      case "":
        // Nothing happens
        break;
      case "north":
      case "n":
        navigateTo("north");
        break;
      case "south":
      case "s":
        navigateTo("south");
        break;
      case "east":
      case "e":
        navigateTo("east");
        break;
      case "west":
      case "w":
        navigateTo("west");
        break;
      case "up":
      case "u":
        navigateTo("up");
        break;
      case "down":
      case "d":
        navigateTo("down");
        break;
        //Dioogue Help
      case "help":
        outputBox.innerHTML = " Here is a list of useful commands: North, South, East, West, Up, Down, Look, Examine, Inventory, Take, Use";
        break;
        //
      default:
        outputBox.innerHTML = " I have no idea what " + "'" + inputTextBox.value.bold() + "'" + " means...";
    } // End switch

    //Clear InputTextBox
    inputTextBox.value = "";
    inputTextBox.setAttribute("placeholder", "");


  } // End KeyPress
}); // End Event listener

displayOut();

@charset "utf-8";
@font-face {
  font-family: 'Terminal';
  /*a name to be used later*/
  src: url(lcd_solid.ttf);
  /*URL to font*/
}
* {
  font-family: Terminal;
  font-size: 18px;
  margin: 0;
  border: 0;
}
body,
html {
  font-family: helvetica;
  font-size: 12px;
  background: #282828;
}
#imgBox {
  margin: 0px auto 0px auto;
  background-image: url("../images/room_0.jpg");
  background-repeat: no-repeat;
  height: 600px;
  width: 1024px;
}
#conBox {
  margin: 0px auto 0px auto;
  position: relative;
  width: 1024px;
  height: 300px;
}
#diologueBox {
  background: #CCC;
  height: 200px;
  clear: both;
  padding: 1px 0px 1px 3px;
  overflow: none;
  position: relative;
}
#diologueBox p {
  margin: 5px;
  left: 0px;
  bottom: 0px;
}
#outputBox {
  background: #CCC;
  height: 50px;
  clear: both;
  padding: 1px 0px 1px 3px;
  overflow: none;
  position: relative;
}
#inputBox {
  position: relative;
  height: 20px;
  background: #C1C1C1;
}
#inputTextBox {
  height: 18px;
  padding: 1px;
  float: right;
  width: 1004px;
  background: #C1C1C1;
}
::-webkit-input-placeholder {
  color: red;
}
:-moz-placeholder {
  /* Firefox 18- */
  color: red;
}
::-moz-placeholder {
  /* Firefox 19+ */
  color: red;
}
:-ms-input-placeholder {
  color: red;
}
#inputTextBox.focus,
input:focus {
  outline: none;
}
#bullet {
  width: 15px;
  float: left;
  padding: 4px 0px 1px 3px;
}

<!DOCTYPE html>
<html lang="en">

<head>
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
  <link rel="stylesheet" type="text/css" href="styles/style.css">
  <meta charset="utf-8">
  <title>Untitled</title>
</head>

<body>
  <div id="imgBox"></div>
  <div id="conBox">
    <div id="diologueBox"></div>
    <div id="outputBox"></div>
    <div id="inputBox">
      <div id="bullet">></div>
      <input id="inputTextBox" type="text" maxlength="60" placeholder="Type commands here, type 'Help' at any time for list of commands" autofocus></input>
    </div>
  </div>

  <script src="script2.js"></script>

</body>

</html>

Answer 1

快速解决方案:像在 css 中所做的那样使用背景图像。

编辑:但是更改 src 属性应该有效，我不确定 jquery 如何处理它。

如果无法使用背景，您可以:

• 拥有您的所有<img>在你的 html 中隐藏/显示它们(速度很快，但需要预先加载所有内容)
• 使用 $("<img/>") 动态创建 img 元素并更换旧的。考虑到您的用例，它在资源方面相当便宜。
• 使用 Canvas 来绘制图像(但为什么不使用背景图像呢？)