javascript - Cannot set property InnerHTML of null

You are almost certainly running your code before the DOM is constructed. Try running your code in a window.onload handler function (but see note below):

window.onload = function() {
    // all of your code goes in here
    // it runs after the DOM is built
}

Another popular cross-browser solution is to put your




• Note that window.onload will wait until all images and subframes have loaded, which might be a long time after the DOM is built. You could also use document.addEventListener("DOMContentLoaded", function(){...}) to avoid this problem, but this is not supported cross-browser. The bottom-of-body trick is both cross-browser and runs as soon as the DOM is complete.