function test1( name ){
    this.name = name;
  }
 
  function test2( name ){
    test1.call(this,name);
    this.say = function(){}
  }
 
  test2.prototype = new test1;
 
  var t = new test2("nihao");
 
  console.log(t);
  console.log(t.constructor);

<form name="demoForm" id="demoForm" method="post" enctype="multipart/form-data" 
onsubmit="uploadAndSubmit();return false;"> 
<p>Upload File: <input type="file" name="file" /></p> 
<p><input type="submit" value="Submit" /></p> 
</form> 
<div>Progessing (in Bytes): <span id="bytesRead"> 
</span> / <span id="bytesTotal"></span> 
</div>

  function uploadAndSubmit() {
    var form = document.forms["demoForm"]; 
 
     if (form["file"].files.length > 0) {
     // 寻找表单域中的 <input type="file" ... /> 标签
     var file = form["file"].files[0];
     // try sending
     var reader = new FileReader(); 
 
     C.log(reader);
     reader.onloadstart = function() {
     // 这个事件在读取开始时触发
     C.log("onloadstart");
     document.getElementById("bytesTotal").textContent = file.size;
     }
     reader.onprogress = function(p) {
     // 这个事件在读取进行中定时触发
     C.log("onprogress");
     document.getElementById("bytesRead").textContent = p.loaded;
     } 
 
     reader.onload = function() {
        // 这个事件在读取成功结束后触发
        console.log("load complete");
     } 
 
     reader.onloadend = function() {
        // 这个事件在读取结束后，无论成功或者失败都会触发
     if (reader.error) {
        C.log(reader.error);
     } else {
        document.getElementById("bytesRead").textContent = file.size;
        C.log(reader.readyState);
     }
     } 
 
        reader.readAsBinaryString(file);
     } else {
        C.log("请选择上传文件");
     }
    }
 
    var C = {
    // console wrapper
    debug: true, // global debug on|off
    quietDismiss: false, // may want to just drop, or alert instead
    log: function() {
        if (!C.debug) return false;
 
        if (typeof console == 'object' && typeof console.log != "undefined") {
            console.log.apply(this, arguments);
        }
        else {
            if (!C.quietDismiss) {
                var result = "";
                for (var i = 0, l = arguments.length; i < l; i++)
                    result += arguments[i] + " ("+typeof arguments[i]+") ";
 
                var elem = document.createElement("textarea");
                elem.innerHTML = result;
				document.body.appendChild(elem);
                }
            }
        }
    }; // end console wrapper.

function create(fun,proto){
    var f=function(){};
    //Copy the object since it is going to be changed.
    for (var x in proto){
        f.prototype[x] = proto[x];
    }
    f.prototype.toString = fun;
    return new f;
}
var fun=function(){alert("a");return "Hello world";}
var obj={x:5}
 
var foo=create(fun,obj);
alert(foo); //Hello world
foo.x=8;
alert(foo.x); // 8
delete foo.x;
alert(foo.x); // 5

(function($) {
 
    $.belowthefold = function(element, settings) {
        var fold = $(window).height() + $(window).scrollTop();
        return fold < = $(element).offset().top - settings.threshold;
    };
 
    $.abovethetop = function(element, settings) {
        var top = $(window).scrollTop();
        return top >= $(element).offset().top + $(element).height() - settings.threshold;
    };
 
    $.rightofscreen = function(element, settings) {
        var fold = $(window).width() + $(window).scrollLeft();
        return fold < = $(element).offset().left - settings.threshold;
    };
 
    $.leftofscreen = function(element, settings) {
        var left = $(window).scrollLeft();
        return left >= $(element).offset().left + $(element).width() - settings.threshold;
    };
 
    $.inviewport = function(element, settings) {
        return !$.rightofscreen(element, settings) && !$.leftofscreen(element, settings) && !$.belowthefold(element, settings) && !$.abovethetop(element, settings);
    };
 
    $.extend($.expr[':'], {
        "below-the-fold": function(a, i, m) {
            return $.belowthefold(a, {threshold : 0});
        },
        "above-the-top": function(a, i, m) {
            return $.abovethetop(a, {threshold : 0});
        },
        "left-of-screen": function(a, i, m) {
            return $.leftofscreen(a, {threshold : 0});
        },
        "right-of-screen": function(a, i, m) {
            return $.rightofscreen(a, {threshold : 0});
        },
        "in-viewport": function(a, i, m) {
            return $.inviewport(a, {threshold : 0});
        }
    });
 
})(jQuery);