在javascript中從var設置圖像的高度和寬度

Question

我正在嘗試將圖像作為背景並適合瀏覽器的尺寸。 但是，我得到： expmrt.html:15 Uncaught TypeError: Cannot set property 'width' of null 。

 //Get the browser legth and height, then after the code is done, time out in 300 miliseconds. function ScreenLoop() { var Width = window.innerWidth; var Height = window.innerHeight; alert("Width: " + Width + " and also Height: " + Height) //Debugging reasons document.getElementById("theimage").width = Width; // Where the error: expmrt.html:15 Uncaught TypeError: Cannot set property 'width' of null) occures for some reason. document.getElementById("theimage").height = Height; setTimeout(ScreenLoop(), 300); }; ScreenLoop(); 

 <img src="tl2fZkc.png" id="theimage" width="50" height="50" alt="theimage" /> 

Answer 1

從窗口調用load事件內的ScreenLoop（）

window.onload = function() {
   ScreenLoop();
}