判断上传图片像素值

gistfile1.txt

var imageSize = false
var inputElement = document.getElementById("input");
inputElement.addEventListener("change", handleFiles, false);
function handleFiles() {
  var fr = new FileReader;

  fr.onload = function() { // file is loaded
      var img = new Image;

      img.onload = function() {
          if(img.width<330 || img.height<185){
            alert("请提供规定尺寸的图片")
            inputElement.value = ""
          }
          else{
            imageSize = true;
          }
      };

      img.src = fr.result; // is the data URL because called with readAsDataURL
  };

  fr.readAsDataURL(this.files[0]); // I'm using a <input type="file"> for demonstrating
}