javascript - Animating array of divs; only the final element is modified -

-

this baffling me @ moment.

i'm experienced programmer looking throw bit of surprise fiancee on countdown page our wedding. desired effect simulated confetti falling behind main page. setup follows:

i have array of divs in javascript. each div absolutely positioned on page. have interval set updates every 50 or milliseconds. on each tick, run loop on array of divs, , calculations , update positions.

problem problem having, however, though can see divs created, stored array, , modified (in case, each has slight randomized rotation) during initialization phase, once tick update position starts, div stored in whatever last slot of array gets position updated. tried hard-coding each div index testing purposes, strictly last element update position. upon printing current "left" , "top" style values each div before , after calculations shows value has been changed, no visible change noticeable. here's basic code:

javascript

var container;            // div have other divs attached var conf = new array();   // array of divs modify var rots = new array();   // rotation of each div var vels = new array();   // velocity of each div var xpos = new array();   // current x value of position in pixels var ypos = new array();   // current y value of position in pixels var xvels = new array();  // x portion of velocity var yvels = new array();  // y portion of velocity  function initialize()     // attached onload event on <body> tag {     container = document.getelementbyid("conf_container");     confettiinit();       // creates, initializes, , displays each div      setinterval(updateconfetti, 42); }  function confettiinit() {     screenheight = window.innerheight;     screenwidth = window.innerwidth;      (var = 0; < 25; ++)   // create 25 confetti flakes     {         // append div in container unique id         container.innerhtml += "<div class='conf' id='conf_" + + "'></div>";         // store element in array         conf[i] = document.getelementbyid("conf_" + i);         // ensure confetti in background, , each z index unique         conf[i].style.zindex = -i - 1;          xpos[i] = window.innerwidth * math.random();  // calculate random x position         conf[i].style.left = xpos[i] + "px";          // set x position of div         ypos[i] =  -40;                               // y position above screen         conf[i].style.top = ypos[i] + "px";           // set y position of div          // calculate random amount of rotation (-30 30 degrees)         rots[i] = math.random() * 60*(math.pi/180) - 30*(math.pi/180);         // set rotation of div         conf[i].style.webkittransform = "rotate(" + -rots[i] + "rad)";          vels[i] = math.random() * 3 + 2;         // calculate random velocity (2-5)         xvels[i] = vels[i] * math.sin(rots[i]);  // x portion of velocity         yvels[i] = vels[i] * math.cos(rots[i]);  // y portion of velocity     } }  function updateconfetti() {     (var = 0; < 25; ++)     {         xpos[i] += xvels[i];   // calculate new x position         ypos[i] += yvels[i];   // calculate new y position         conf[i].style.left = xpos[i] + "px";   // set div's x position         conf[i].style.top = ypos[i] + "px";    // set div's y position          // if confetti piece leaves viewing area...         if (xpos[i] < -50 ||             xpos[i] > window.screenwidth + 10 ||             ypos[i] > window.screenheight + 10)         {             // send top , reinitialize             xpos[i] = window.innerwidth * math.random();              conf[i].style.left = xpos[i] + "px";              ypos[i] = -40;             conf[i].style.top = ypos[i] + "px";              rots[i] = math.random() * 60*(math.pi/180) - 30*(math.pi/180);             conf[i].style.webkittransform = "rotate(" + -rots[i] + "rad)";              vels[i] = math.random() * 3 + 2;             xvels[i] = vels[i] * math.sin(rots[i]);             yvels[i] = vels[i] * math.cos(rots[i]);         }     } }

css

div.conf {     height: 29px;     width: 50px;     background-image: url("images/confettiyellow.gif");     position: absolute; }  #conf_container {     left: 0px;     top: 0px;     width: 100%;     height: 100%;     position: absolute;     overflow: hidden; }

it's wrong divs creation. start works if in conventional way, this:

var d = document.createelement("div"); d.classname = "conf"; container.appendchild(d); conf[i] = d;

Comments

Post a Comment

Popular posts from this blog

c++ - Function signature as a function template parameter -

-
i'd use function signature template argument. works great classes, when try same trick function templates, msvc throws error: error c2768: 'func' : illegal use of explicit template arguments here's code: template <typename signature> void func(); template <typename r, typename a1> void func<r(a1)>(); what should make work? you cannot partially specialize function template, not supported language. can create partially specialized class template static member function, , possibly trampoline function instantiate class template , invoke static function. something this: namespace detail { template<typename signature> struct helper; template<typename r, typename a1> struct helper<r(a1)> { static void call() { // stuff r , a1... } }; } template<typename signature> void func() { detail::helper<signature>::call(); }
Read more

How to call a javascript function after the page loads with a chrome extension? -

-
there's function on page want call after loads. not own page, can't insert html it. can please provide specific examples how chrome extension or greasemonkey? (function submitaction() ). both chrome extensions , greasemonkey offer ways specify when script inject if executed. in chrome extension, you set in manifest : "content_scripts": [ { "run_at" : "document_idle", in greasemonkey compatible userscripts, set in metadata // @run-at document-end in both cases, have add script if want ensure resources loaded when function executed : document.addeventlistener('load', submitaction);
Read more

algorithm - What are some ways to combine a number of (potentially incompatible) sorted sub-sets of a total set into a (partial) ordering of the total set? -

-
i have sorting problem i'm pretty sure doesn't have canonical "answer" - has number of different approaches, each pros/cons. i'm interested in hearing different approaches. suppose bunch of people {p_i | i=1,...,m} ranking favorite ice cream flavors. in total there n different flavors, single person p_i ranks n_i << n flavors or familiar with. i'm interested in combining these sub-rankings plausible overall ranking of n flavors. for concrete situation: m , n both 1000 (by coincidence), , each n_i 20 . can assume there's enough overlap in flavors people rank such no flavor "isolated". again, i'm interested in hearing different ways approach this, if there isn't single clear answer. thanks! one way approach problem construct directed cyclic graph representing of constraints on ordering of elements. nodes in graph represent different elements compared , have edge first node second node if had ranked first e
Read more