Question

未确定的检查功能返回--- 马上它命中img.onload它会跳到checkize的末尾

var valor1 = 2;
var valor2 = 6;
var valor3 = 10;
function showResult() {

    var result = parseInt(valor1 + valor2 + valor3);
    console.log(result);


    if (result >= 0 && result <= 20) {
        newResult = result;
     result = window.open();

       result.document.write("<b> Su resultado es:</b> " + newResult +
         " <br> <b> Muy Bajo </b> :  Con esta puntuación debes saber que"
      );
   }
}


showResult();

Answer 1

你缺少关闭主要功能的大括号，因为你的if (sizes.width != 600 || sizes.height != 800)在img.load里面是错误的，把它改成看起来如下，你正在比较确切的长度所以只有精确的尺寸图像会返回true我已经更改了代码，以便在加载后将图像附加到正文并将条件if (sizes.width <= 600 || sizes.height <= 800) {更改为800 x 600，以使图像小于console没有附加到正文，并且错误被抛出function checksize(files) { var img = new Image(); img.onload = function() { var sizes = { width: img.width, height: img.height }; if (sizes.width <= 600 || sizes.height <= 800) { console.log("Error: Image size should be greater 600 x 800px , image " + img.src + ' could not be loaded'); return false; } else { $('body').append(img); return true; } }; img.src = files; }你可以改变条件

function checksize(files) {
  var img = new Image();

  img.onload = function() {
    var sizes = {
      width: img.width,
      height: img.height
    };

    if (sizes.width <= 600 || sizes.height <= 800) {
      console.log("Error: Image size should be greater 600 x 800px , image " + img.src + ' could not be loaded');
      return false;
    } else {
      $('body').append(img);
      return true;
    }

  };
  img.src = files;

}

var files = ['https://www.animalfriends.co.uk/app/uploads/2017/04/21150218/iStock-524369488.jpg', 'https://static.pexels.com/photos/356378/pexels-photo-356378.jpeg', 'https://www.pets4homes.co.uk/images/articles/238/large/44186f3f7c3e962827e462a95d7206bc.jpg'];

for (var i = 0; i < files.length; i++) {
  checksize(files[i]);
}

img {
  width: 250px;
  height: 250px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

{{1}}

Answer 2

您正在尝试将事件处理程序添加到图像元素的load事件中。这样做

  var img = new Image();
  $(img).on("load",function(){
      var sizes = {
       width: this.width,
       height: this.height
       };
      if (sizes.width != 600 || sizes.height != 800) 
      {
         alert("Error: Image size should be 600 x 800px");
         return false;

      }
     else 
     {
       return true;
     }


    });
   img.src = _URL.createObjectURL(files[0]);

请注意，如果要在设置图像时触发该功能，则需要在事件函数之后放置img.src。将其放在函数内将导致递归

我如何等待从img.onload获得响应

2 个答案: