Image upload control for Safari on iPad that pulls the selected image out of the control and renders it, all client side

gistfile1.js

function addUploadControl() {

  if(document.getElementById("imageUpload")===null) {

   var fileInputContainer=document.createElement("div");
   var fileInput=document.createElement("input");
   fileInputContainer.style.backgroundColor="white";
   fileInputContainer.style.padding="10px";
   fileInputContainer.style.borderColor="black";
   fileInputContainer.style.borderRadius="10px";
   fileInputContainer.style.borderWidth="2px";
   fileInputContainer.style.borderStyle="solid";
   fileInputContainer.style.opacity="1";
   fileInputContainer.style.zIndex=1200;
   fileInputContainer.style.top="700px";
   fileInputContainer.style.left="0px";
   fileInputContainer.style.position="absolute";

   fileInputContainer.appendChild(document.createTextNode("Image"));

   fileInput.style.opacity="0";
   fileInput.type="file";
   fileInput.id="imageUpload";
   
   var drawImage=function(e) {
    
    var firstImage=document.getElementById("imageUpload").files[0];
    var reader=new FileReader();
    
    reader.onloadend=function(e) {
     
     var imgString=e.target.result;
     imgString=imgString.replace("data:","data:image/jpeg;");
     var existingImageElement=document.getElementById("imagePreview");
     
     if(existingImageElement===null) {
      
      var imgElement=document.createElement("img");
      imgElement.id="imagePreview";
      imgElement.style.top="800px";
      imgElement.style.left="0px";
      imgElement.style.width="100%";
      imgElement.style.position="absolute";
      
      existingImageElement=document.body.appendChild(imgElement);
     };

     existingImageElement.src=imgString;
    };
    
    var blob=firstImage.webkitSlice(0,firstImage.size);
    reader.readAsDataURL(blob);
   };
   
   fileInput.addEventListener("change",drawImage);
   document.body.appendChild(fileInputContainer);

   fileInputContainer.appendChild(fileInput);
   
  }
}