Develop Reference

Using map\reduce with nested elements in javascript

I have a search form that allows the user to add as many search terms as they like. When the user enters all of the search terms and their search values and clicks search, a text box will be updated with the search terms. I've got this working with a for loop, but I'm trying to improve my dev skills and am looking for a way to do this with map\filter instead.
Here's the code I'm trying to replace:
var searchTerms = $("#search-form").find(".mdc-layout-grid__inner");
var searchString = "";
for(var i = 0; i < searchTerms.length - 1; i ++)
{
var select = $(searchTerms[i]).find(".select2-selection")[0];
var selectText = $(select).select2('data')[0].text + ":";
var textBox = $(searchTerms[i]).find(".mdc-text-field__input")[0];
searchString = searchString += selectText.replace(/\./g,"").replace(/ /g,"") + textBox.value;
if(i < searchTerms.length - 1)
{
searchString = searchString += " ";
}
}
$("#er-search-input").val(searchString);
Here's a codepen of the current solution.
i'm trying the below, but I get the feeling I'm miles away:
const ret = searchTerms.map((u,i) => [
$($(u[i]).find(".select2-selection")[0]).select2('data')[0].text + ":",
$(u[i]).find(".mdc-text-field__input")[0].value,
]);
My question is, is it possible to do this with map?

Firstly you're repeatedly creating a jQuery object, accessing it by index to get an Element object only to then create another jQuery object from that. Instead of doing this, you can use eq() to get a specific element in a jQuery object by its index.
However if you use map() to loop through the jQuery object then you can avoid that entirely by using this to reference the current element in the iteration. From there you can access the required elements. The use of map() also builds the array for you, so all you need to do is join() the results together to build the required string output.
Finally, note that you can combine the regex expressions in the replace() call by using the | operator, and also \s is more robust than using a whitespace character. Try this:
var $searchTerms = $("#search-form").find(".mdc-layout-grid__inner");
var searchString = $searchTerms.map(function() {
var $searchTerm = $(this);
var selectText = $searchTerm.find('.select2-selection').select2('data')[0].text + ':';
var $textBox = $searchTerm.find('.mdc-text-field__input:first');
return selectText.replace(/\.|\s/g, "") + $textBox.val();
}).get().join(' ');
$("#er-search-input").val(searchString);

Javascript code doesn't load the page

I have a little problem with this javascript code, when I add more site on the list, the page doesn't load. I have to add more than 200 site.
I'm a noob with javascript. Can someone explain what is the problem, what
I'm doing wrong?
<script language="JavaScript" type="text/javascript">
var a = new Array(
'notiziepericolose.blogspot.it',
'ilcorrieredellanotte.it',
'ilmattoquotidiano.it',
'ilfattonequotidiano.com',
'rebubblica.altervista.org',
'coriere.net'
);
var aa = a.slice();
aa.sort();
document.write("<ol>");
document.write("<b>");
for (i = 0; i < a.length; i=i+1) {
document.write('<li id="demo'+i+'">'+a[i]+'</li>');
}
document.write("</b>");
document.write("</ol>");
</script>

I guess the first thing is that document.write is very rarely used now as there a better and more efficient ways of adding things (elements, text etc) to the DOM (more on that later). In addition, in your case, what you don't realise is that document.write is not like echo or println; each time it is used it clears the document, which is probably why you're not seeing anything appear. In other words, The results of multiple document.writes are not cumulative.
The second thing is that there are better ways of "labelling" elements than with ids, particularly if there are a lot of them on the page like you'll have. Again, there are now much better ways of targetting elements, or catching events than there were ten or fifteen years ago.
So, let's talk about your code.
You can quickly create a array using the [] brackets.
var arr = [
'notiziepericolose.blogspot.it',
'ilcorrieredellanotte.it',
'ilmattoquotidiano.it',
'ilfattonequotidiano.com',
'rebubblica.altervista.org',
'coriere.net'
];
You don't have to create a copy of the array in order to sort it - it can be done in place:
arr.sort();
I'm going to keep your loop but show you a different way of concatenating strings together. Some people prefer adding strings together, but I prefer this way, and that's to create an array of the little parts of your string and then join() them together**.
// Set l as the length, and create an output array called list
for (var i = 0, l = arr.length, list = []; i < l; i++) {
// I've changed things here. I've added a class called item
// but also changed the element id to a data-id instead
var li = ['<li class="item" data-id="', i, '">', arr[i], '</li>'];
// Push the joined li array of strings into list
list.push(li.join(''));
}
Assuming you have an element on your page called "main":
HTML
<div id="main"></div>
JS
You can add the list array as an HTML string to main by using [insertAdjacentHTML] method:
var main = document.getElementById('main');
// Note that I've given the ordered list an id called list
var HTML = ['<ol id="list"><b>', list.join(''), '</b></ol>'].join('');
main.insertAdjacentHTML('beforeend', html);
OK, so that's pretty easy. But I bet you're asking how you can target the individual items in the list so that if I click on one of them it alerts what it is (or something).
Instead of adding an event listener to each list item (which we could but it can work out performatively expensive the more items you have), we're going to attach one to the ol element we added that list id to and catch events from the items as they bubble up:
var ol = document.getElementById('list');
Then an event listener is added to the list that tells us what function (checkItem) is called when a click event is raised:
ol.addEventListener('click', checkItem);
Our function uses the event (e) to find out what the event's target was (what item was clicked), and alerts its text content.
function checkItem(e) {
alert(e.target.textContent);
}
You can see all this working in this demo. Hope some of this was of some help.
** Here's another way of sorting, and looping through the array using reduce:
var list = arr.sort().reduce(function (p, c, i) {
return p.concat(['<li class="item" data-id="', i, '">', c, '</li>']);
}, []).join('');
DEMO

if ES6 is possible for you, you can do it like this:
var a = new Array(
'notiziepericolose.blogspot.it',
'ilcorrieredellanotte.it',
'ilmattoquotidiano.it',
'ilfattonequotidiano.com',
'rebubblica.altervista.org',
'coriere.net');
var aa = a.slice();
var mL = document.getElementById('mylist');
aa.sort().map(el => {
var li = document.createElement("li");
var b = document.createElement("b");
var t = document.createTextNode(el);
b.appendChild(t);
li.appendChild(b);
mL.appendChild(li);
});
<ol id="mylist"></ol>

If you're using an Array, you can use a forEach instead of a loop.
var domUpdate = '';
var websites = ['notiziepericolose.blogspot.it','ilcorrieredellanotte.it','ilmattoquotidiano.it','ilfattonequotidiano.com','rebubblica.altervista.org','coriere.net'];
websites.forEach(function(website, index){
domUpdate += '<li id="website-' + ( index + 1 ) + '"><b>' + website + '</b></li>';
});
document.getElementById('hook').innerHTML = '<ol>' + domUpdate + '</ol>';
<div id="hook"></div>

I'm thinking document.write is the wrong choice here, as it seems to be clearing the document. https://developer.mozilla.org/en-US/docs/Web/API/Document/write Probably you want to bind the new content to existing html through document.getElementById or something like that

Assigning javascript array elements class or id for css styling

I'm trying to assign class and id to items in an array I created in js and input into my html. I'm doing this so I can style them in my stylesheet. Each item will not be styled the same way.
I'm a beginner so trying to keep it to code I can understand and make it as clean as possible, i.e. not making each of these items an element in the html.
This part works fine:
var pool =['A','B','3','J','R','1','Q','F','5','T','0','K','N','C','R','U']
var letters = pool.join('');
document.getElementById('key').innerHTML = letters;
This part not so much:
var char1 = letters[1];
char1.classList.add('hoverRed');
There is a similar question here that didn't work for me, it just showed [object][object][object] when I ran it.

Your code attempts to apply a style to an array element, but CSS only applies to HTML. If you wish to style one character in a string, that character must be wrapped in an HTML element (a <span> is the best choice for wrapping an inline value).
This code shows how to accomplish this:
var pool =['A','B','3','J','R','1','Q','F','5','T','0','K','N','C','R','U']
var letters = pool.join('');
// Replace a specific character with the same character, but wrapped in a <span>
// so it can be styled
letters = letters.replace(letters[1], "<span>" + letters[1] + "</span>");
// Insert the letters string into the div
var theDiv = document.getElementById('key');
// Inject the string into the div
theDiv.innerHTML = letters;
// Get a reference to the span:
var theSpan = theDiv.querySelector("span");
// Add the style to the <span> that wraps the character, not the character itself
theSpan.classList.add('hoverRed');
.hoverRed {
color:red;
}
<div id="key"></div>
And, this snippet shows how you could apply CSS to any letter:
var pool =['A','B','3','J','R','1','Q','F','5','T','0','K','N','C','R','U'];
// Leave the original array alone so that it can be manipulated any way needed
// in the future, but create a new array that wraps each array element within
// a <span>. This can be accomplished in several ways, but the map() array method
// is the most straight-forward.
var charSpanArray = pool.map(function(char){
return "<span>" + char + "</span>";
});
// Decide which character(s) need CSS applied to them. This data can come from anywhere
// Here, we'll just say that the 2nd and 5th ones should.
// Loop through the new array and on the 2nd and 5th elements, apply the CSS class
charSpanArray.forEach(function(element, index, array){
// Check for the particular array elements in question
if(index === 1 || index === 4){
// Update those strings to include the CSS
array[index] = element.replace("<span>","<span class='hoverRed'>");
}
});
// Now, turn the new array into a string
var letters = charSpanArray.join('');
// For diagnostics, print the string to the console just to see what we've got
console.log(letters);
// Get a reference to the div container
var theDiv = document.getElementById('key');
// Inject the string into the div
theDiv.innerHTML = letters;
.hoverRed {
color:red;
}
<div id="key"></div>

You're on the right track, but missed one key thing.
In your example, pool contains characters. When you combine them using join, you get a string. Setting that string as the innerHTML of an element doesn't give the string super powers, it's still just a string.
In order to get a classList, you need to change your letters into elements and work with them.
I've included an es6 example (and a working plunker) of how to get the functionality you want below.
let pool = ['A','B','3','J','R','1','Q','F','5','T','0','K','N','C','R','U']
const letterToElement = function(char) {
//Create the element
let e = document.createElement("SPAN");
//Create the text node
let t = document.createTextNode(char);
//Put the text node on the element
e.appendChild(t);
//Add the class name you want
e.className += "hoverRed";
return e;
};
//create your elements from your pool and append them to the "key" element
window.onload = function() {
let container = document.getElementById("key");
pool.map(l => letterToElement(l))
.forEach(e => container.appendChild(e));
}
https://plnkr.co/edit/mBhA60aUCEGSs0t0MDGu

how to split the textarea into parts in javascript

I am trying to open the 5 urls inputted by the user in the textarea
But the array is not taking the url separately instead taking them altogether:
function loadUrls()
{
var myurl=new Array();
for(var i=0;i<5;i++)
{
myurl[i] = document.getElementById("urls").value.split('\n');
window.open(myurl[i]);
}
}

You only should need to split the text contents once. Then iterate over each item in that array. I think what you want is:
function loadUrls() {
var myurls = document.getElementById("urls").value.split('\n');
for(var i=0; i<myurls.length; i++) {
window.open(myurls[i]);
}
}

Here's a working example:
var input = document.getElementById('urls');
var button = document.getElementById('open');
button.addEventListener('click', function() {
var urls = input.value.split('\n');
urls.forEach(function(url){
window.open(url);
});
});
<button id="open">Open URLs</button>
<textarea id="urls"></textarea>
Note that nowadays browsers take extra steps to block popups. Look into developer console for errors.

There are a couple issues I see with this.
You are declaring a new Array and then adding values by iterating through 5 times. What happens if they put in more than 5? Or less?
split returns a list already of the split items. So if you have a String: this is a test, and split it by spaces it will return: [this, is, a, test]. There for you don't need to split the items and manually add them to a new list.
I would suggest doing something like:
var myUrls = document.getElementById("urls").value.split('\n');
for (var i = 0; i < myUrls.length; i++) {
window.open(myUrls[i]);
}
However, as others suggested, why not just use multiple inputs instead of a text area? It would be easier to work with and probably be more user friendly.

Basically:
document.getElementById("urls").value.split('\n');
returns an array with each line from textarea. To get the first line you must declare [0] after split the function because it will return the first item in Array, as split will be returning an Array with each line from textarea.
document.getElementById("urls").value.split('\n')[0];
Your function could simplify to:
function loadUrls(){
var MyURL = document.getElementById("urls").value.split('\n');//The lines
for(var i=0, Length = MyURL.length; Length > i; i++)
//Loop from 0 to length of URLs
window.open(
MyURL[i]//Open URL in array by current loop position (i)
)
}
Example:
line_1...
line_2...
... To:
["line_1","line_2"]

JavaScript Asp.net repeating controls

I am trying to do the folowing with Asp.net 3.5/IIS
A web form with a top level repeatable form. So basically a Order->Products->ProductsParts kinda of scenerio. Order is only one. Product is repeatable. Each product has repeatable products parts. The product and product part have a whole bunch of fields so I cannot use a grid.
So, I have add/remove buttons for Product and within each product add/remove buttons for each product part.
That is my requirement. I have been able to achieve add/remove after some research using jquery/js. How, do i capture this data on the server? Since javascript is adding and removing these controls they are not server side and I don't know how to assign name attributes correctly. I am trying following javascript but it ain't working:
function onAddProperty(btnObject){
var previous = btnObject.prev('div');
var propertyCount = jquery.data(document.body, 'propertyCount');
var newDiv = previous.clone(true).find("*[name]").andSelf().each(function () { $(this).attr("name").replace(($(this).attr("name").match(/\[[0-9]+\]/), cntr)); }); ;
propertyCount++;
jquery.data(document.body, 'propertyCount', propertyCount);
//keep only one unit and remove rest
var children = newDiv.find('#pnlUnits > #pnlUnitRepeater');
var unitCount = children.length;
var first = children.first();
for (i = 1; i < unitCount; i++) {
children[i].remove();
}
newDiv.id = "pnlPropertySlider_" + propertyCount;
newDiv.insertBefore(btnObject);
}
I need to assign name property as array so that I can read it in Request.Form
Fix for not updating ids not working:
var newDiv = previous.clone(true).find("input,select").each(function () {
$(this).attr({
'name': function () {
var name = $(this).attr('name');
if (!name) return '';
return name.replace(/property\[[0-9]+\]/, 'property' + propertyCount);
}
});
}).end().insertBefore(btnObject);

The issue looks like the following line:
$(this).attr("name").replace(($(this).attr("name").match(/\[[0-9]+\]/), cntr));
This statement doesn't do anything. Strings in JavaScript an immutable, and .replace only returns the string with something replaced.
You would then have to actually set the attr("name") to the new string that has the replaced value:
http://api.jquery.com/attr/
I can't help much more without seeing your HTML.