Tips to improve performance of Javascript - javascript

I have a requirement where I need to set the height of each row of a table based on the corresponding row in another table.The table has around 500 rows.
I have written the below Javascript, but the performance is really bad around 8000 ms.
How can I make this faster, appreciate any tips .
var start = new Date().getTime();
var rows = document.getElementById("table1").rows;
var dup_rows = document.getElementById("table2").rows;
var num_rows = rows.length;
var num_dup = dup_rows.length;
for (var i = 0; i < num_rows; ++i) {
var hg = rows[i].offsetHeight;
rows[i].style.height = hg +'px';
dup_rows[i].style.height = hg +'px';
}
var end = new Date().getTime();
var time = end - start;
alert('Execution time: ' + time);
Based on the Suggestion to edit the tables outside of DOM, I tried the below, but the outerHeight / offsetHeight returns 0 when the table is removed from DOM.
clone_small = $('#table2').clone();
clone_main_tab = $('#table1').clone();
$("#table2").remove();
$("#table1").remove();
$(clone_main_tab).find("tr").each(function(i) {
var hg = 0;
hg = $(this).offsetHeight; // If I hard code the height it works
// alert(hg);
$(this).height(hg);
clone_small.find("tr").eq(i).height(hg);
});
How can I set the height of these rows outside the DOM ?

Remove the element that you are modifying from the DOM, then re-insert them when you are done modifying them. This prevents the browser having to reflow the document with every change, only doing it once when you're all finished.

Isn't dup_rows[i].style.height = rows[i].style.height better?

I was finally able to achieve some improvement in performance by using the below code
$clone_table1 = $('#table1').clone();
$clone_table2 = $('#table2').clone();
$('#table2').remove();
$trow2 = $('#table1').find('tr');
$trow = $clone_table1.find('tr');
$trow3 = $clone_table2.find('tr');
$trow.each(function(i) {
var hg = 0;
hg = $trow2.eq(i).outerHeight();
$(this).height(hg);
$trow3.eq(i).height(hg);
});
$parent2.append($clone_table2);
$('#table1').remove();
$parent1.append($clone_table1);

Related

Can I divide a text box by paragraph in Google Slides using Apps Script?

I am trying to design some code in Apps Script that can be put on any Google Slides presentation and split every text box by paragraphs so every paragraph has its own text box.
I started out using var shape = slide.insertShape(SlidesApp.ShapeType.TEXT_BOX, 50, 50, 300, 300); to make the new text boxes like google describes to use in most of its tutorials but it 'couldn't identify the TEXT_BOX type' so I found .insertTextBox and that seems to work better but I've found other problems.
I can use .getParagraphs to find the number of paragraphs in a text box but I can't tell if it doesn't include the contents of each paragraph or if I'm just not using the correct command to get the text from the paragraph. I have also tried to find an alternative to find the beginning of each paragraph and divide the text from there but I can't find a command for that either. Maybe would I have to use .indexOf to find each /n or /r, or is there a simpler way?
I'm also having a problem where my equations to divide up the text box size are giving me undefined answers and I've tried declaring the variables as numbers but it just makes things worse.
function myFunction() { // get slides in the presentation and establish 'for' variables
var slide = SlidesApp.getActivePresentation().getSlides();
var i;
var j;
var k;
for (i = 0; i < slide.length; i++) { // get the text boxes on each slide
var text = slide[i].getShapes();
for (j = 0; j < text.length; j++) { // get the location of and the paragraphs in each textbox (locations don't work)
var top = text[j].getTop;
var left = text[j].getLeft;
var width = text[j].getWidth;
var height = text[j].getHeight;
var paragraph = text[j].getText().getParagraphs();
for (k = 0; k < paragraph.length; k++){ // make a textbox for each paragraph distributed vertically over the original textbox
var content = text[j].getRange(paragraph[k]); //I was hoping this would fill with the contents of current paragraph
var shapeheight = height / paragraph.length; //NaN and I don't know why
var shapetop = height * k + top; //also doesn't work these should all be numbers
slide[i].insertTextBox(content, left, shapetop, width, shapeheight);
}
text[j].remove(); //delete original textbox on slide
}
}
}
Here are pictures of what I'm trying to do:
Slide before intended changes
Approximate slide after intended changes
I believe your goal as follows.
You want to split each paragraph in a text box as each text box on Google Slides.
You want to achieve this using Google Apps Script.
Modification points:
In your script,
getTop, getLeft, getWidth and getHeight are the method. So please add ().
About var content = text[j].getRange(paragraph[k]), getRange has no arguments.
About var shapeheight = height / paragraph.length, in this case, this can be put outof the for loop.
About var shapetop = height * k + top, in this case, that might be var shapetop = shapeheight * k + top.
When above points are reflected to your script, it becomes as follows.
Modified script:
function myFunction() {
var slide = SlidesApp.getActivePresentation().getSlides();
var i;
var j;
var k;
for (i = 0; i < slide.length; i++) {
var text = slide[i].getShapes();
for (j = 0; j < text.length; j++) {
var top = text[j].getTop(); // Modified
var left = text[j].getLeft(); // Modified
var width = text[j].getWidth(); // Modified
var height = text[j].getHeight(); // Modified
var paragraph = text[j].getText().getParagraphs();
var shapeheight = height / paragraph.length; // Modified
for (k = 0; k < paragraph.length; k++) {
var content = paragraph[k].getRange().asString(); // Modified
var shapetop = shapeheight * k + top; // Modified
slide[i].insertTextBox(content, left, shapetop, width, shapeheight);
}
text[j].remove();
}
}
}
Note:
In the current stage, it seems that AutoFit cannot be set. By this, when slide[i].insertTextBox(content, left, shapetop, width, shapeheight) is used, the text deviates a little from the box. So in this case, how about not using shapeheight? In this case, please modify slide[i].insertTextBox(content, left, shapetop, width, shapeheight); as follows.
var t = slide[i].insertTextBox(content);
t.setLeft(left);
t.setTop(shapetop);
t.setWidth(width);
References:
getTop()
getLeft()
getWidth()
getHeight()
getRange()
insertTextBox(text)

Making divs fill up a containing div?

I've been searching the site for an answer, and nothing I've come across seems to help. I'm trying to make it so that a default (and eventually user-specified) number of divs fill up the containing div like a grid. I'm trying to figure out how to make the size of the boxes I append to the parent change depending on how many are added, while always filling up the div, if that makes sense. So for instance, if I specify 9, I should have 3 rows and 3 columns. If I specify 62, then I'm looking for 16 rows and 16 columns, always filling up (or coming close to, anyway) the containing div. Here's a JSfiddle I have so far: https://jsfiddle.net/psyonix/1g9p59bx/1/ Here's the code as it is:
var d = ("<div class='square'></div>");
function createGrid(numSquares){
for(var i = 0; i < numSquares; i++){
$('#g_area').append(d);
}
var squareSize = Math.floor(580/numSquares );
$('.square').height(squareSize);
$('.square').width(squareSize);
};
$(document).ready(function(){
createGrid(64);
});
The only issue you had was setting the square size to 1/64th of the height instead of 1/(64^.5) of the height. Essentially you where just making one row. https://jsfiddle.net/1g9p59bx/7/
var d = ("<div class='square'></div>");
function createGrid(numSquares){
var gridContainer = $('#g_area');
for(var i = 0; i < numSquares; i++){
gridContainer.append(d);
}
var squareSize = Math.floor(580/(Math.sqrt(numSquares)) );
$('.square').height(squareSize);
$('.square').width(squareSize);
};
$(document).ready(function(){
createGrid(64);
});
I would create a little jqueryplugin for that. You can call it in every container you like: containerForGrid.createGrid(cols, rows)
(function($){
$.fn.createGrid = function(cols, rows) {
// get width and height of sorrounding container
var w = this.width()
var h = this.height()
// calculate width and height of one cell
var colWidth = w / cols
var rowHeight = h / rows
// loop over all rows
for(var i = rows; --i;){
// loop over all cols
for(var j = cols; --j;){
$('<div>').css({
width:colWidth,
height:rowHeight,
float:'left'
}).appendTo(this)
}
}
}
})(jQuery)
jQuery('div').createGrid(10,10)
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div style="width:1000px;height:500px">
</div>

jQuery counting elements with attributes

I have a jQuery code wich is counting some divs where certain Breakfast board are found as below
var board_bb1 = $('div[data-board="Bed And Breakfast"]').length;
var board_bb2 = $('div[data-board="Breakfast"]').length;
var board_bb3 = $('div[data-board="Breakfast Buffet"]').length;
var board_bb4 = $('div[data-board="Breakfast (Full Breakfast)"]').length;
var board_bb5 = $('div[data-board="Continental Breakfast"]').length;
var board_bb8 = $('div[data-board="Bed and Breakfast"]').length;
var board_bb6 = $('div[data-board="Full Breakfast"]').length;
var board_bb7 = $('div[data-board="Breakfast (Continental Breakfast)"]').length;
var board_bb = board_bb1 + board_bb2 + board_bb3 + board_bb4 + board_bb5 + board_bb6 + board_bb7 + board_bb8;
The attributes from data-board are coming from an API service, and sometimes is breakfast sometimes is Breakfast, bed And Breakfast etc.
Is there a way to simply the above code to count all the divs who has the word Breakfast in data-board
$("div[data-board*='Breakfast']").length
The *= part will look for any attribute containing the word breakfast.
IF you are not using jQuery in your project, in modern browsers this will work to:
document.querySelectorAll("div[data-board*='Breakfast']").length;
To complete it: a cross-browser solution that will work all the way back to IE5.5
var allDivs = document.getElementsByTagName("div");
var count = 0;
for (var i = 0, i < allDivs.length; i++)
{
if (allDivs[i].getAttribute("data-board") && allDivs[i].getAttribute("data-board").match(/Breakfast/) )
{
count++;
}
}
After this count will return the amount of divs containing the word Breakfast in the data-board attribute
You can use ~ operator
$("div[data-board~='Breakfast']").length

Force begin rendering with javascript

I've an ajax-call that will give me a 500 row return. Each row will create a HTML-object that will be added to the DOM. This all works fine, but it's slow.
I would like to add 20, then render what is done, and then continue to add the last 480. However, I can't figure out how to force rendering.
The code is something like this:
for (i = 0; i < 500; i += 1) {
$(newdata[i]).insertAfter('#object');
}
Where newdata is a textstring, for example
"<p>hello world</p>"
Edit
I might have left out some critical information in my post. The nodes are not to be inserted in order. It's a tree and each node has a parent that I know about. And each parent is garanteed to be inserted before the node. So I can't just append nodes after eachother since they might be in different branches.
Stop inserting one node at the time, insert collections of nodes instead.
It's not the loop that's slow, it's DOM manipulation that is slow, and inserting 500 DOM nodes one node at the time will be slow.
var nodes = $();
for (i = 0; i < 20; i++) {
nodes.append(newdata[i])
}
$('#object').after(nodes);
var more_nodes = $();
for (i = 20; i < 500; i++) {
more_nodes.append(newdata[i])
}
$('#object').after(more_nodes);
If you do it like this, it will probably be ten times faster, and you don't have to insert 20, then 480 etc.
Give the rendering code time to run. Write a few rows, call setInterval() to let other code run, and continue:
function renderLines(newdata) {
var len = newdata.length;
var sofar = 0;
var obj = $('#object');
var renderSome = function() {
for ( var i = 0; (i < 20) && ((i + sofar) < len); ++i )
{
$(newdata[i + sofar]).insertAfter(obj);
}
sofar += 20;
if (sofar < len)
setTimeout(renderSome, 10);
};
setTimeout(renderSome, 10);
}

How to add a large number of items to an HTML selectObject

I need to populate eight selectObject pulldown objects on a page with several thousand (8192) items each. I'm currently doing this in Javascript the only way I know how:
var iCount;
var option1;
var selectObject1 = document.getElementById('ifbchan');
for(iCount = 0; iCount < 8192; iCount++)
{
option1=document.createElement("option");
option1.text = "Out " + iCount;
option1.value=iCount;
try
{
selectObject1.add(option1, selectObject1.options[null]);
}
catch (e)
{
selectObject1.add(option1, null);
}
}
selectObject1.selectedIndex = 0;
This method works properly but is extremely slow! Each of these 8K loops takes something like 10 seconds to complete. Multiply by 8 different loops and the problem is obvious. Is there any other way to add large numbers of items to a drop down list that would be faster? Any faster alternatives to the drop down control for presenting a large list of items? Thanks for any ideas.
~Tim
I'd try the following:
var elements = ""
var i;
for(i= 0; i < 8192; i++){
elements += "<option value='"+ i + "'>Out " + i + "</option>";
}
document.getElementById("ifbchan").innerHTML = elements;
This way you only perform one action on the DOM per loop not 8000+.
Oh and here's one I prepared earlier: http://jsfiddle.net/3Ub4x/
Few things before the answer.
First of all I do not think that the best way to do this is a server side implementation. If you can do something on the client you should do this and not touch your server (if it is not security related).
Second thing - why exactly do you need 8000 elements in select list? Think as a user of your app, who would like to scroll through 8000 elements just to select his element? As it was mentioned before - autocomplete sounds much more suitable.
And right now is an answer:
Your original approach is here: it takes approximately 1724 miliseconds to complete for 10000 elements (You can see this by running the script and checking inspector).
var start = new Date();
var n = 10000;
var iCount;
var option1;
var selectObject1 = document.getElementById('ifbchan');
for(iCount = 0; iCount < n; iCount++)
{
option1=document.createElement("option");
option1.text = "Out " + iCount;
option1.value=iCount;
try
{
selectObject1.add(option1, selectObject1.options[null]);
}
catch (e)
{
selectObject1.add(option1, null);
}
}
selectObject1.selectedIndex = 0;
var time = new Date() - start;
console.log(time);
I do not like a lot of this code (it is too many lines) so I will rewrite it in jquery.
var start = new Date();
var n = 10000;
for (var i = 0; i<n; i++){
$("#ifbchan").append("<option value="+i+">"+i+"</option>")
}
var time = new Date() - start;
console.log(time);
The next fiddle is here. Much less lines, and some time improvement. Now it is 1312 milliseconds. But it append new element in every loop.
The next fiddle get rid of this.
var start = new Date();
var n = 10000;
var html = '';
for (var i = 0; i<n; i++){
html += "<option value="+i+">"+i+"</option>";
}
$("#ifbchan").append(html);
var time = new Date() - start;
console.log(time);
Wow, now it is only 140 milliseconds.
for (var i = 0; i<n; i++){
select.append('<option value='+i+'>'+i+'</option>');
}
Beware, this doesn't work in IE. See this link -
Using innerHTML to Update a SELECT – Differences between IE and FF

Categories