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Lolu chungechunge lwabekwa kunqolobane. Uyacelwa ubuze umbuzo omusha uma udinga usizo.

Certain files with looping javascript load very slow

  • Akukho zimpendulo
  • 3 zinale nkinga
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I have a HTML page of approximately 11,000 lines. It represents a z/OS ISPF editor screen. To save space and make it a bit more fancy it's made up of several sections. One of them just contains generated sequence numbers using code like

// seq = 10992 var a = [];

   if (seq <= 9999)
     z = '00
 ' for (var i = 0; i < seq; i++) a[i] = (i+10001).toString().substr(1); document.write(' '+a.join(z)+'00
'); } else { z = '0
 ' for (var i = 0; i < seq; i++) a[i] = (i+100001).toString().substr(1); document.write(' '+a.join(z)+'0
'); }


The other javascript on the page is:

// var fs2=0; // the actual fs2 of the fixed-width text. var fs=0; // the actual number of pixels width of each character. var ss=0; // dimensions of a browser scrollbar (note: ss will be NEGATIVE)

 function ge(x) {return document.getElementById(x);}
 function gs(x) {return document.getElementById(x).style;}
 function setwidth() { // do initial sizing calculations and layout
 var thisContainer = document.getElementById('mainarea');
 if (thisContainer)
    var onClickAction = 'scrollmain();';
    thisContainer.onscroll = new Function(onClickAction);
 ss=ge('scrolltest').offsetHeight;                    // get the height of a single line div without scrollbars
 gs('scrolltest').overflow='scroll';                  // allow the scrollbars to show
 ss-=ge('scrolltest').offsetHeight;                   // find the difference (i.e. the height of a scrollbar - assume height of horizontal bar = width of vertical bar!
 var wh=window.innerHeight?window.innerHeight:document.documentElement.clientHeight?document.documentElement.clientHeight:document.body.clientHeight;
 var ww=window.innerWidth?window.innerWidth:document.documentElement.clientWidth?document.documentElement.clientWidth:document.body.clientWidth;
     // determine the actual window inner height+width
 fs2=Math.floor(ww/40);                               // "Courier New" is twice as high as it is wide; we need 80 columns; this is an approximation only
 while ((Math.floor(ge('measure').scrollWidth) > Math.floor(ww+ss)) && fs2>1) // iteratively reduce fs2 until 80 columns fits on-screen
   fs2-=1;'normal '+fs2+'px/'+(fs2+4)+'px "Courier New"';
   gs('measure').font='normal '+fs2+'px/'+(fs2+4)+'px "Courier New"';
 gs('fixed').width=ge('measure').scrollWidth+'px';    // set the width of the header area
 fs=ge('measure').scrollWidth / 80;                   // get the width of a character
 gs('headers').height=(4+fs2)+'px';                   // limit the height of the headers
 gs('fixed').height=(8+(2*fs2))+'px';                 // fix the height of the header at just two rows
 gs('mainarea').width=(ge('measure').scrollWidth-(fs*8)-ss)+'px'; // set the width of the main area
 gs('mainarea').height=(8+(wh+ss)-(6*fs2))+'px';      // set the main area height
 gs('leftarea').height=(8+(wh+ss)-(6*fs2)+ss)+'px';   // set the left area height
 gs('measure').display='none';                        // don't display our 80-character measure
 gs('scrolltest').display='none';                     // don't display the scrollbar measuring div
 scrollmain();                                        // set up the initial column numbers
 function scrollmain() { // update the column indicators
 var main=ge('mainarea');
 var col='0000'+Math.floor((fs+(fs/2)+main.scrollLeft)/fs);   // get the leftmost column number
 ge('colfrom').innerHTML=col.substr(col.length-5,5);          // trim it and display

 ge('colto').innerHTML=col.substr(col.length-5,5);            // trim and display the rightmost column number
 ge('leftarea').scrollTop=main.scrollTop;                     // scroll the left area in sync with the main area
 gs('topofdata').left=main.scrollLeft+'px';                   // reposition the top of data bar
 gs('bottomofdata').left=main.scrollLeft+'px';                // reposition the bottom of data bar


The code was never fast, but on FF4 is absolutely sucks! File can be provided on request, 56K .RAR, 71K .ZIP.