javascript - setTimeout works only when the callback function is called -


i'm trying calculate time of appearance of specific dom element on viewport; when element appears set it's time initial value of zero. , each time element visible users(inside viewport of screen) make settimeout increases it's time 1 every second. , when element disappeared remove callback.

//thanks https://stackoverflow.com/a/33979503/4614264 function isdominviewport(element, fn) {     $(window).scroll(function () {         var top_of_element = $(element).offset().top;         var bottom_of_element = $(element).offset().top + $(element).outerheight();         var bottom_of_screen = $(window).scrolltop() + $(window).height();         var top_of_screen = $(window).scrolltop();          if ((bottom_of_screen > top_of_element) && (top_of_screen < bottom_of_element)) {             fn(1);         }         else {             fn(0);         }     }); }  var poststimerarray=[];//array hold `settimeout` each post id $("div.container").bind('domsubtreemodified', function () {     var posts = $("div.post").each(function(i, obj) {         if(!$(obj).attr("data-visited")){//if didn't visit post before bind actions it.             //analyzepost(obj);             $(obj).attr("data-visited", "1");//set post visited             $(obj).attr("data-seentime", "0");//set initial time 0             var id=$(obj).attr("id");             isdominviewport(obj, function (istrue) {                 if(istrue) {//if element in viewport start timer                     if(!poststimerarray[id]){                         poststimerarray[id]=settimeout(function(){                             $(obj).attr("data-seentime",                                 (parseint($(obj).attr("data-seentime"))+1) + ""                             );                         }, 1000);                     }                     console.log($(obj).attr("data-seentime"));                 }                 else {//if element has disappeared viewport stop timer                     if(poststimerarray[id]){                         cleartimeout(poststimerarray[id]);                         poststimerarray[id]=undefined;                         console.log("removed");                     }                 }                 console.log(poststimerarray);             });         }     }); });

what i'm expecting data-seentime increase every second when post visible in viewport, code increases it's value when post in viewport , i'm scrolling page; ie. if there's no scrolling ,the data-seentime value won't increase.

to give more explanation problem, happens

  • the post marked visited.
  • data-seentime set zero
  • after scroll first time
    • if post in viewport
      • if i'm scrilling => value of data-seentime increases
      • else => nothing happends
    • else doing nothing

but i'm expecting is

  • the post marked visited.
  • data-seentime set zero
  • after scroll first time
    • if post in viewport => value of data-seentime increases
    • else doing nothing

what problem; why increment happens if i'm scrolling in page?


Comments

Post a Comment

Popular posts from this blog

Sort a complex associative array in PHP -

this question has answer here: php sort array subarray value 5 answers i have associative array in php like: $newarray1 = array ( [producta] => array ( [link] => http://sanjosespartan.com/blog/products/agile-java-development/ [visitcount] => 4 ) [productd] => array ( [link] => http://sanjosespartan.com/blog/products/intro-to-go/ [visitcount] => 1 ) [productg] => array ( [link] => http://sanjosespartan.com/blog/products/node-js-for-developers/ [visitcount] => 1 ) [productb] => array ( [link] => http://sanjosespartan.com/blog/products/beginning-mysql/ [visitcount] => 1 ) [productc] => array ( [link] => http://sanjosespartan.com/blog/products/computer-networks/ [visitcount] => 1 ) ...
Read more

vb.net - How to ignore if a cell is empty nothing -

how use roscolor() ignore value (like empty cell) ? color row if value upper 5 when there nothing in cell, want ignore roscolor() apply, how? public sub roscolor() integer = 0 quotedatagridview1.rows.count() - 1 step +1 dim val integer val = quotedatagridview1.rows(i).cells(3).value if val = vbempty quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.white elseif val < 5 quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.red elseif val > 5 , val < 10 quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.lightyellow end if next end sub you can check empty value following public sub roscolor() integer = 0 quotedatagridview1.rows.count() - 1 step +1 dim val = quotedatagridview1.rows(i).cells(3).value if isdbnull(val) or val nothing quotedatagridview1.rows(i).defaultcellstyle.backcolor = color.white ...
Read more

recursion - Can every recursive algorithm be improved with dynamic programming? -

i first year undergraduate csc student looking competitive programming. recursion involves defining , solving sub problems. understand, top down dynamic programming (dp) involves memoizing solutions sub problems reduce time complexity of algorithm. can top down dp used improve efficiency of every recursive algorithm overlapping sub problems? dp fail work , how can identify this? the short answer is: yes. however, there constraints. obvious 1 recursive calls must overlap. i.e. during execution of algorithm, recursive function must called multiple times same parameters. lets truncate recursion tree memoization. can use memoization reduce number of calls. however, reduction of calls comes price. need store results somewhere. next obvious constraint need have enough memory. comes not-so obvious constraint. memory access requires time. first need find result stored , maybe copy location. in cases, might faster let recursion calculate result instead of loading somewher...
Read more