Help converting JavaScript click function to onLoad_问答_开发者

I'm trying to convert a JavaScript function that ran off a click event to launch on page load and window resize. As you can see below, I commented out the section governing the click event and added the last line "window.onload," and manually added the class="resizerd" to the element it was working with.

The function isn't running at all. Chrome's Dev tools are showing "Uncaught TypeError: Cannot set property 'prevWidth' of undefined" Did I mess up the syntax somewhere? Any advice for how to launch this on load?

Thank you!

//var clicked =  document.getElementById("buttonImportant")

  var resizeeContainer = document.getElementById('video_container');
  var resizee = resizeeContainer.getElementsByTagName('video')[0];

  /*clicked.addEventListener('click',function(){
  if( resizeeContainer.className.lastIndexOf("resizerd")>=0 ){
  }
  else
  {
      resizeeContainer.className="resizerd";
  }*/
  myResizerObject.prevWidth = resizee.offsetWidth;
  myResizerObject.prevHeight = resizee.offsetHeight;
  myResizerObject.Init();
  //},false);


    myResizerObject.prevWidth = resizee.offsetWidth;
    myResizerObject.prevHeight = resizee.offsetHeight;
    myResizerObject.Init();

    var RESIZER = function(){ 

        this.prevWidth = resizee.offsetWidth;
        this.prevHeight = resizee.offsetHeight;

        this.resizee = resizeeContainer.getElementsByTagName('video')[0];
        this.resizeeContainer = resizee.parentNode;
        this.resizeeStyle = this.resizee.style;

        var ratio = this.resizee.offsetHeight/this.resizee.offsetWidth;
        var that = this;

        this.Init = function(){
            if( that.resizeeContainer.className.lastIndexOf("resizerd")>=0 )
            {
                var resizeeContOffsetWidth = that.resizeeContainer.offsetWidth;
                var resizeeOffsetWidth = that.resizee.offsetWidth;
                var resizeeContOffsetHeight = that.resizeeContainer.offsetHeight;
                var resizeeOffsetHeight = that.resizee.offsetHeight;

                if(that.prevWidth!= resizeeContOffsetWidth)
                {
                    that.prevWidth = resizeeContOffsetWidth;
                    var desired = resizeeContainer.offsetHeight/resizeeContainer.offsetWidth;
                    if(desired>ratio){
                        that.resizeeStyle.width=resizeeContOffsetWidth*desired+resizeeContOffsetWidth*desired+"px";
                        that.resizeeStyle.left = -1*(resizeeOffsetWidth-resizeeContOffsetWidth)/2+'px';
                    }
                    else{ 
                     that.resizeeStyle.cssText="width:100%;height:auto;position:fixed;";
                    }
                }

                if(that.prevHeight!=resizeeContOffsetHeight)
                { 
                    that.prevHeight = resizeeContOffsetHeight;
                    var desired = resizeeContOffsetHeight/resizeeContOffsetWidth;  
                    if(desired>ratio){  console.log(ratio);
                        //that.resizeeStyle.top = '0px';
                        that.resizeeStyle.left = -1*(resizeeOffsetWidth-resizeeContOffsetWidth)/2+'px';开发者_JAVA技巧
                        that.resizeeStyle.width = resizeeContOffsetHeight*desired+resizeeContOffsetHeight/desired+'px';
                    }
                    else
                    {
                        that.resizeeStyle.top = -1*(resizeeOffsetHeight-resizeeContOffsetHeight)/2+'px';

                    }
                }

            }
        };
    };

    var myResizerObject = new RESIZER();
    window.onresize = myResizerObject.Init;
    window.onload = myResizerObject.Init;

Did you try to execute the function through the <body> tag?

Like:

<body onload="myfunction();">

Try calling the entire resize javascript function in the OnLoad="myfunction();" event of the Body of the page. I have done this to resize the page everytime it loads and it works just fine.

You have this line:

 myResizerObject.prevWidth = resizee.offsetWidth;

That is probably giving the error. You've done nothing to declare myResizerObject so it cannot have a property prevWidth.

Somewhere down there you do

var myResizerObject = new RESIZER();

I suspect you want those lines in a more reasonable order :)

Such code should work just fine:

var myResizerObject = new RESIZER();

function UpdateResizerObject() {
    var resizeeContainer = document.getElementById('video_container');
    var resizee = resizeeContainer.getElementsByTagName('video')[0];
    myResizerObject.prevWidth = resizee.offsetWidth;
    myResizerObject.prevHeight = resizee.offsetHeight;
    myResizerObject.Init();
}

window.onload = function() {
    UpdateResizerObject();
};

window.onresize = function() {
    UpdateResizerObject();
};

Have it after you define the RESIZER class though.

Your mistake was calling the object instance variable before creating it.

Edit: some basic debug.. add alerts to the function like this:

this.Init = function(){
   alert("Init called.. container: " + that.resizeeContainer);
   if (that.resizeeContainer)
      alert("class: " + hat.resizeeContainer.className);
   if( that.resizeeContainer.className.lastIndexOf("resizerd")>=0 )
   {
      ...
   }
}

And see what you get.