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I am trying to change my background image every 5 seconds. How should I go about this?

window.onload = function () {

  function Timer() {
    window.setInterval("changeImage()", 5000);
  }

  function changeImage() {   
    var BackgroundImg["./Img/Bg1.jpg",
                      "./Img/Bg2.jpg",
                      "./Img/Bg3.jpg",
                      "./Img/Bg4.jpg"];
    var i = Math.floor((Math.random() * 3));
    var bgImg = document.body.style.backgroundImage();
    bgImg.url = BackgroundImg[i];
  }
}

I am trying to change my background image every 5 seconds. How should I go about this?

window.onload = function () {

  function Timer() {
    window.setInterval("changeImage()", 5000);
  }

  function changeImage() {   
    var BackgroundImg["./Img/Bg1.jpg",
                      "./Img/Bg2.jpg",
                      "./Img/Bg3.jpg",
                      "./Img/Bg4.jpg"];
    var i = Math.floor((Math.random() * 3));
    var bgImg = document.body.style.backgroundImage();
    bgImg.url = BackgroundImg[i];
  }
}
  • javascript
  • html
Share Improve this question edited Jan 9, 2016 at 6:18 Pang 10.1k146 gold badges86 silver badges124 bronze badges asked Jan 9, 2016 at 5:39 Kyle McCarthyKyle McCarthy 411 gold badge1 silver badge5 bronze badges 3
  • 1 See stackoverflow./questions/34669608/… – guest271314 Commented Jan 9, 2016 at 5:48
  • 1 @Kyle McCarthy: i suggest instead getting random values. make a array with totalimage length. shuffle it. and proceed from index 0. if you are reaching final index. then again shuffle and proceed. dueto this you can avoid same image Repetition – Arunkumar Vasudevan Commented Jan 9, 2016 at 5:52
  • What do you see when you add breakpoints and step through the code? – user663031 Commented Jan 9, 2016 at 6:33
Add a ment  | 

3 Answers 3

Reset to default 3

You can make few changes

1.Not sure from where you are calling Timer function (better if have camelCase)

function Timer() {
    window.setInterval("changeImage()", 5000);
  }

Instead you can directly use 

setInterval(changeImage, 5000);

changeImage is a callback

2.Could not make out what is this line mean

var bgImg = document.body.style.backgroundImage();

Unsure if can attach a function to style property.

Anyway this below snippet can be useful

window.onload = function () {
     // Array of Images
      var backgroundImg=["https://encrypted-tbn0.gstatic./images?q=tbn:ANd9GcRyB57zuc4bms-hDtWMa-4BZvscIlJDm4r7a9WLaO4SAxUvKM-DDA",
                        "https://encrypted-tbn0.gstatic./images?q=tbn:ANd9GcQBinSpWOvAtkxjmkf709O3rjH2ObRbWAEn9s0JcWaeL6LMtCbOrQ",
                        "https://encrypted-tbn0.gstatic./images?q=tbn:ANd9GcRKY4J2qIFqkuDnABMzeypywbMSZL1cleS8vpySz0KD02wOYORU1g",
                        "https://encrypted-tbn1.gstatic./images?q=tbn:ANd9GcRQkdQT0zN0xDVP-VuvwojSbS5dOstX14eZvJCOWNPxKJ5dWTIc"
                        ]

        setInterval(changeImage, 5000);
       function changeImage() {   
        var i = Math.floor((Math.random() * 3));

        document.body.style.backgroundImage = "url('"+backgroundImg[i]+"')";

      }
    }

DEMO

you are accessing style incorrectly

window.onload = function () {

    function changeImage() {   
        var BackgroundImg=["./Img/Bg1.jpg",
            "./Img/Bg2.jpg",
            "./Img/Bg3.jpg",
            "./Img/Bg4.jpg"
        ];
        var i = Math.floor((Math.random() * 4));
        document.body.style.backgroundImage = 'url("' + BackgroundImg[i] + '")';
    }
    window.setInterval(changeImage, 5000);
}

Also, if possible (usually is) don't pass a string to window.setInterval - use as above

Here's a solution to your question. Hope it helps!

<!DOCTYPE html>

<html>
<head>
  <title>change picture</title>
  <script type = "text/javascript">
      function displayNextImage() {
          x = (x === images.length - 1) ? 0 : x + 1;
          document.getElementById("img").src = images[x];
      }
      function changeImage() {
          setInterval(displayNextImage, 5000);
      }

      var images = [], x = -1;
      images[0] = "http://www.planwallpaper./static/images/desktop-year-of-the-tiger-images-wallpaper.jpg";
      images[1] = "http://www.planwallpaper./static/images/background-gmail-google-images_FG2XwaO.jpg";
      images[2] = "http://www.planwallpaper./static/images/beautiful-sunset-images-196063.jpg";
  </script>
  </head>
  <body onload = "changeImage()">
   <img id="img" src="http://www.planwallpaper./static/images/beautiful-sunset-images-196063.jpg"/>
  </body>
  </html>

本文标签： htmlMake JavaScript change background image every 5 secondsStack Overflow

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