Develop Reference

How not to make <br> a tag

<script>
var y="<br>"
function repeater(num){
for (var i=0;i<num;i++)
{document.write(y) }
}
document.write(repeater(4))
</script>
My goal is to make the tag appear
4 times, not the actual breaks. The result shows undefined.

Since the question is asking for Javascript solution not JQuery (since no jQuery tags), I'll add the answer using Javascript.
<script>
var y = "<br>"
function repeater(num) {
for (var i=0; i < num; i++) {
document.body.innerText += y;
}
}
repeater(4);
</script>
or maybe you need to set a text into the spesific element (<div id="app"><div>)? no problem, we can improve the code a little bit.
<script>
var y = "<br>"
function repeater(el, num) {
for (var i=0; i < num; i++) {
el.innerText += y;
}
}
var el = document.getElementById('app');
repeater(el, 4);
</script>

<script>
var res = "";
var y="<br>";
function repeater(num){
for (var i=0;i<num;i++) {
res = res + y;
}
$('#customDiv').text(res);
}
(repeater(4))
You can put a custom <div id="customDiv"></div> inside your html file.

Returning html code in javascript

I want to print html code in Javascript code.
I want to open and close the bottom line of five li tags. How can I do this with a for loop
jQuery(document).ready(function () {
InsertLi();
});
function InsertLi(){
var count = 5;
for (var i = 0; i < count; i++) {
var codeBlock = ' <li>' + i + '</li>';
$(".bildirimMetin").html(codeBlock);
}
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="bildirimMetin">
</ul>

You need to use append function instead. html function every time overrides your html content with the new content and you get only the last one. Also create your string with 5 li-s and then call the append at the end to work with DOM one time and have more performance.
function InsertLi() {
var count = 5;
var codeBlock = '';
for (var i = 0; i < count; i++) {
codeBlock += ' <li>' + i + '</li>';
}
$(".bildirimMetin").append(codeBlock);
}
jQuery(document).ready(function () {
InsertLi();
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="bildirimMetin"></ul>
If you have only one item with bildirimMetin class, it will be better to use id instead of class.

Well, another solution, close to your code, with html, store all strings in your variable via += then you must define your variable before for loop also move your html after it. Your current code not working because it just store last string not all.
InsertLi();
function InsertLi() {
var count = 5;
var codeBlock = '';
for (var i = 0; i < count; i++) {
codeBlock += '<li>' + i + '</li>';
}
$(".bildirimMetin").html(codeBlock);
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul class="bildirimMetin">
</ul>

you had a couple issues. One was overwriting the inner HTML instead of appending. The other was a syntax issue.
function InsertLi(){
var count = 5;
for (var i = 0; i < count; i++) {
var codeBlock = ' <li>' + i + '</li>';
$(".bildirimMetin").append(codeBlock);
}
}
jQuery(document).ready(function () {
InsertLi();
}
);

Add alphabets dynamically as html row increments

How to ensure i have a dynamic increment of Alphabets in a new cell on left side, next to each cell in a row which is dynamically created based on the option chosen in Select. This newly generated alphabet will be considered as bullet points/serial number for that particular row's text box.
jsfiddle
js code
$(document).ready(function(){
var select = $("#Number_of_position"), table = $("#Positions_names");
for (var i = 1; i <= 100; i++){
select.append('<option value="'+i+'">'+i+'</option>');
}
select.change(function () {
var rows = '';
for (var i = 0; i < $(this).val(); i++) {
rows += "<tr><td><input type='text'></td></tr>";
}
table.html(rows);
});
});
html
<select id="Number_of_position">
</select> <table id="Positions_names">
</table>

This is essentially a base26 question, you can search for an implementation of this in javascript pretty easily - How to create a function that converts a Number to a Bijective Hexavigesimal?
alpha = "abcdefghijklmnopqrstuvwxyz";
function hex(a) {
// First figure out how many digits there are.
a += 1; // This line is funky
var c = 0;
var x = 1;
while (a >= x) {
c++;
a -= x;
x *= 26;
}
// Now you can do normal base conversion.
var s = "";
for (var i = 0; i < c; i++) {
s = alpha.charAt(a % 26) + s;
a = Math.floor(a/26);
}
return s;
}
So you can do
$(document).ready(function(){
var select = $("#Number_of_position"), table = $("#Positions_names");
for (var i = 1; i <= 100; i++){
select.append('<option value="'+i+'">'+i+'</option>');
}
select.change(function () {
var rows = '';
for (var i = 0; i < $(this).val(); i++) {
rows += "<tr><td>" + hex(i) + "</td><td><input type='text'></td></tr>";
}
table.html(rows);
});
});
Heres the example http://jsfiddle.net/v2ksyy7L/6/
And if you want it to be uppercase just do
hex(i).toUpperCase();
Also - this will work up to any number of rows that javascript can handle

if i have understood you correctly, that's maybe what you want:
http://jsfiddle.net/v2ksyy7L/3/
I have added an array for the alphabet:
var alphabet = "abcdefghijklmnopqrstuvwxyz".split("");
and then added the output to your "render" loop:
rows += "<tr><td>" + alphabet[i] + " <input type='text'></td></tr>";

Why does this for loop not display in my div using JavaScript?

I want to display the content in my div but the code won't work. Please show me how to do it.
<!DOCTYPE html>
<html>
<body>
<p id="display"></p>
<script>
var i;
for (i = 0; i < 11; i++) {
var disp = "the number is " + i;
console.log(disp);
}
disp = document.getElementById("display").innerHTML;
</script>
</body>
</html>
How can I get the loop to display my variable in my selected div? Which part of my code is wrong? please help.

Tehre are multiple problems
<p id="display"></p>
<script>
var i;
//initialize the value
var disp = '';
for (i = 0; i < 11; i++) {
//concatenate the value of disp so that new value will be added to the previous content other wise the values will be overwritten
disp += "the number is " + i;
console.log(disp);
}
//assign value of disp to the elemet innerHTML
document.getElementById("display").innerHTML = disp;
</script>

Set the innerHTML inside the for loop.
for (var i = 0; i < 11; i++) {
var disp = "the number is " + i;
document.getElementById("display").innerHTML = disp;
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
}
IF you want to display all the content at once
var disp = ''; // Assign empty string
for (var i = 0; i < 11; i++) {
disp += " the number is " + i; // Concat message
}
document.getElementById("display").innerHTML = disp; // Add into html
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Because you never write anything to your HTML page. You just display it in your console. And later you assign the HTML content of the #display element to the variable disp, which doesn't make any sense:
disp = document.getElementById("display").innerHTML;
This is how it will work
<!DOCTYPE html>
<html>
<body>
<p id="display"></p>
<script>
var i;
for(i=0; i<11; i++){
var disp = "the number is " + i;
// This just writes to the javascript console
console.log(disp);
// This writes in the #display element on your page
document.getElementById("display").innerHTML += disp + '<br>';
}
</script>
</body>
</html>

var i;
for(i=0; i<11; i++){
var disp = "the number is " + i;
console.log(disp);
}
document.getElementById("display").innerHTML = disp;

Something like this should be fine
function createDivs(){
var pContainer = document.getElementById("display");
var i;
for(i = 0; i < 11; i++){
var message = "the number is " + i;
console.log(message);
var element = document.createElement("div");
element.innerHTML = message;
pContainer.appendChild(element);
}
disp = document.getElementById("display").innerHTML;
};
createDivs();

jQuery .append() after offset

I have this:
<div id="testcase">abcdefghijklmnopqrstuvwxyz</div>
I would like to add this: <span> with an offset.
So when I for example would have the JS function: addSpan(4) this would happen:<div id="testcase">abcd<span>efghijklmnopqrstuvwxyz</div>
To visualise what I'm looking for:
function addSpan(i){
$('#testcase').append('<span>', i);
}

Use slice and concatinate...
function addSpan(i){
var content = $("#testcase").html();
var before = content.slice(0, i);
var after = content.slice(i + 1);
$("#testcase").html(before + "<span></span>" + after);
}

Here another wut i tired LIVE DEMO
$("#btn_clck").on('click', function () {
var gText = $("#testcase").html();
var getlength = gText.length;
var finalValue = "";
for (var i = 0; i < getlength; i++) {
var setData = gText.charAt(i);
if (i == 4) {
finalValue += '<span></span>'
}
finalValue += setData;
}
$("#testcase").text(finalValue);
});
but i think Steini's answers was better