如何在按键按下时对多个按键进行编码？ （JavaScript的）

Question

I'm trying to have each key, correspond to different images when pressed. (Ex: When "A" is pressed = image1 appears, When "S" is pressed = image2 appears, and so on.)

I was able to get the "S" Key to work, but not the A. I'm trying to do this for the whole row on the keyboard ("A","S","D","F","G","H","J","K","L")

*PS. Im still a beginner :)

This is my code:

<img src="images/giphy.gif" width="800" height="400" alt=""/>

<script>
  document.addEventListener("keydown", keyDownBody, false);

  function keyDownBody(e) {
    var keyCode = e.keyCode;
    if(keyCode==65) {
      myFunction();
    }
  }

function myFunction() {
var x = document.createElement("IMG");
x.setAttribute("src", "images/giphy1.gif")
x.setAttribute("width", "800");
x.setAttribute("height", "400");
x.setAttribute("alt", "The Pulpit Rock");
document.body.appendChild(x);
}

function keyDownBody(e) {
    var keyCode = e.keyCode;
    if(keyCode==83) {
      myFunction();
    }
  }

function myFunction() {
var x = document.createElement("IMG");
x.setAttribute("src", "images/sun.gif")
x.setAttribute("width", "800");
x.setAttribute("height", "400");
x.setAttribute("alt", "The Pulpit Rock");
document.body.appendChild(x);
}
</script>

Answer 1

You have declared the same function multiple times. You could merge them to make it work, and also make your code more readable. An example:

document.addEventListener("keydown", keyDownBody, false);

function keyDownBody(e) {
  var keyCode = e.keyCode;
  switch (keyCode) {
    case 65:
        loadImage("images/giphy1.gif", "The Pulpit Rock");
        break;
    case 83:
        loadImage("images/sun.gif", "The Pulpit Rock");
        break;

    // Etc.
  }
}

function loadImage(uri, alt) {
    var x = document.createElement("IMG");
    x.setAttribute("src", uri)
    x.setAttribute("width", "800");
    x.setAttribute("height", "400");
    x.setAttribute("alt", alt);
    document.body.appendChild(x);
}

This way you can add as many keys as you wish.

Alternatively, you could load the images dynamically if you put them in an array:

var images = [{
      uri: 'images/giphy1.gif',
      alt: 'A',
    }, {
      uri: 'images/sun.gif',
      alt: 'Some text',
    }, 
    // Etc.
];

function keyDownBody(e) {
  var keyCode = e.keyCode;

  var index = keyCode - 65;
  if (typeof images[index] !== 'undefined')
  {
    var image = images[index];
    loadImage(image.uri, image.alt);
  }
}

Answer 2

 var keys_to_div = []; keys_to_div[65] = "1"; // A key keys_to_div[66] = "2"; // B key window.onkeydown = function(e) { if (keys_to_div[e.keyCode]) document.getElementById(keys_to_div[e.keyCode]).style.display = "block"; } window.onkeyup = function(e) { if (keys_to_div[e.keyCode]) document.getElementById(keys_to_div[e.keyCode]).style.display = "none"; } 

 img { width: 50px; height: 50px; display: none; } 

 <img src="http://images4.fanpop.com/image/photos/22100000/The-letter-A-the-alphabet-22186936-2560-2560.jpg" id="1"> <img src="http://www.drodd.com/images15/letter-b23.gif" id="2"> 

Answer 3

You just need to add more conditions

function keyDownBody(e) {
    var keyCode = e.keyCode;
    if(keyCode==83) {
      myFunction("images/giphy1.gif");
    }

    if(keyCode==85) {
      myFunction("images/giphy2.gif");
    }

    if(keyCode==87) {
      myFunction("images/giphy3.gif");
    }
  }

function myFunction(imageName) {
  var x = document.createElement("IMG");
  x.setAttribute("src", imageName)
  x.setAttribute("width", "800");
  x.setAttribute("height", "400");
  x.setAttribute("alt", "The Pulpit Rock");
  document.body.appendChild(x);
}

Answer 4

Use same keydown EventListener to all the keys like

document.addEventListener("keydown", keyDownBody, false);

  function keyDownBody(e) {
    var keyCode = e.keyCode;
    if(keyCode==65) {
      myFunction("images/giphy1.gif");
    }
    else if(keyCode==83) {
      myFunction("images/sun.gif");
    }
  }

function myFunction(t) {
var x = document.createElement("IMG");
x.setAttribute("src", t)
x.setAttribute("width", "800");
x.setAttribute("height", "400");
x.setAttribute("alt", "The Pulpit Rock");
document.body.appendChild(x);
}