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Try it, This is the best tutorial site:
https://www.tutorialspoint.com/reactjs/
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Sorry for the belated reply, but the best I could tell you is on Udemy, search for React and the course from instructor Maximilian Shwarzmuller is the best one. It covers all aspect of react, plus redux and redux-saga, along with deployment on a web server and some backend.
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I have coding of a quiz with an array which has questions and options. First time the function is called successfully but when restarting the quiz, the function is not invoked.
This is the code which is not working:
$(document).on('click', '#restart', function() {
showQuestions();
});
The whole coding is:
// Showing questions and options
var x = "";
var i = 0;
function showQuestions() {
document.getElementById('holder').
innerHTML = x;
for (j = 0; j < words[i].options.length; j++) {
if (i < words.length) {
$('#holder').append("<div
id="+words[i].options[j] + "
class='alternatives'>" +
words[i].options[j] + "
</div>");
}
}
if (i < words.length) {
$('#holder').append('<div
id="quest">' +
words[i].question + '</div>');
i++;
}
}
showQuestions();
// Calling function on click of alternatives
$('#holder').on('click',
'.alternatives', function() {
showQuestions();
});
score = 0;
k = 0;
$(document).on('click',
'.alternatives', function() {
let guess = this.id;
if (k < words.length) {
var correct = words[k].answer;
k++;
}
if (guess === correct) {
score++;
}
if (score <= words.length) {
z = score;
document.getElementById('summary').innerHTML = z;
}
if (k >= words.length) {
$('#holder').fadeOut();
$('#restart').fadeIn();
}
});
// Restarting Quiz
$(document).on('click', '#restart', function() {
$(this).fadeOut();
$('#holder').fadeIn();
showQuestions();
});
modified 24-May-19 7:53am.
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You could make your question clearer by using <pre> tags* around the code block, indenting properly, and removing all those redundant blank lines, so it looks like:
$(document).on('click', '#restart', function() {
$(this).fadeOut();
$('#holder').fadeIn();
showQuestions();
});
*or use the code button at the top of the edit window.
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You can call this function on restart button onClick event...
function restartquiz(){
$(document).on('click', function() {
showQuestions();
});
}
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Explain the working of timers in JavaScript? Also elucidate the drawbacks of using the timer, if any?
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It is very rude to copy and paste your actual homework question here. Very lazy. You can't even put it into your own words. All you have to do is pay attention in class and then google if you foget. Here's the first result. JavaScript Timing Events[^]
Social Media - A platform that makes it easier for the crazies to find each other.
Everyone is born right handed. Only the strongest overcome it.
Fight for left-handed rights and hand equality.
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The function displays values of options property of array in separate divs. I want to give each div a unique id, which I have given, but the first displayed divs are replaced by totally different divs on click; so I am unable to give ids to each div. I want that divs should remain same and only the values should change on click. Presently the ids that I have given are removed when next values are displayed on click. How can I achieve that? Thanks for your suggestions.
<button id="btnNext" onclick="showOptions();"> Options </button>
<div id="container"> </div>
var antonyms = [
{
question: "soft",
options: ["dark", "white", "heavy", "hard", "down", "pretty", "butter", "cotton"],
answer: "hard"
},
{
question: "beautiful",
options: ["pretty", "ugly", "handsome", "wonderful", "up", "high", "cheerful", "black"],
answer: "ugly"
},
]
function showOptions(q)
{
let qHtml = '<div class="option">' + q.question + '</div>';
qHtml += q.options.map(o => '<div class="option">' + o + '</div>').join("");
return qHtml;
}
```
let container = document.getElementById("container");
let button = document.getElementById("btnNext");
let qIdx = 0;
container.innerHTML = showOptions(antonyms[qIdx]);
button.addEventListener("click", function()
{
qIdx += 1;
if (qIdx < antonyms.length)
container.innerHTML = showOptions(antonyms[qIdx]);
else
button.disabled = true;
});
```
$('#container div').each(function(eq, el) {
el = $(el);
if (typeof(el.attr('id')) === "undefined") {
el.attr('id', 'box-' + eq);
}
});
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I don't quite follow where you are lost, but if you want the id to be unique then keep a global variable counter and add it to the end of each div's id and then increment it.
Social Media - A platform that makes it easier for the crazies to find each other.
Everyone is born right handed. Only the strongest overcome it.
Fight for left-handed rights and hand equality.
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I have a source file in XML which I need to read in with javascript.
Now I use the XmlDocument object, but I find it very user-unfriendly.
Is there a library someone can recommend that will do the job better?
thanks!
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It would probably help if you explained exactly what the problem is. SDKs/libraries are generally designed to help developers solve problems; user-friendliness are rarely a consideration.
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Right now I'm using constructs like this:
xml.getElementsByTagName("group")[0].childNodes[1].childNodes[0].childNodes[0].childNodes[0].nodeValue;
to get a value from some part of the XML.
But the XML could change slightly and so this goes wrong. I "could" check each and every node for the right value, but that would end up being terribly complicated as far as I can see. Mainly because it seems that a node is not only a tag, but also the value in the tag.
I tried XML transforms (xsl) , but the transform to html didn't work. (I looked it up and apparently there are some issues with javascript and xml transforms)
So simply put, I need to traverse the node tree (or "tag tree") in a simpler and easier way.
obsolete to say XML is not really my thing 
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V. wrote: xml.getElementsByTagName("group")[0].childNodes[1].childNodes[0].childNodes[0].childNodes[0].nodeValue;
is exactly the sort of code that leads to trouble. You need to traverse in a logical fashion starting at the top node, and at each point check whether the child is the correct one you are looking for.
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indeed, that's the whole point. I find this XmlDocument system far too complicated or I'm using it wrong somehow. I'm not against loops and if's/switch statements, but it would end up ridiculously complicated in my opinion.
eg.
<xml>
<mytag>the value of this tag</mytag>
</xml>
if you get to the tag "mytag" you get 2 nodes: one for the "mytag" and one for the contents of mytag ("the value of this tag").
In my mind, I would call "getValue" or something on the mytag node to get the contents. In XmlDocument you need to call the childnode first before getValue. Which is just weird.
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Modern versions of Javascript have querySelector() and querySelectorAll(), which are a lot easier to use than traversing the tree - check your documentation (and document object) to see if you have them. You can basically pick out nodes using CSS selectors.
As an alternative there is XPath - it uses expressions to drill down into the tree, just not in the familiar CSS-way that querySelector and querySelectorAll do it.
The querySelector/querySelectorAll functions are available in all the modern browsers, but it looks like XPath is in everything apart from Internet Explorer.
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thanks! I'll certainly have a look at that.
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Greetings experts.
I have used this script before on page with Next, Previous, Submit code and it worked then.
Now, I am trying to use it on a similar application where users will fill the first page and click Next to go to the next page.
Usually, if a required field is not completed and the user clicks Next, a message will display warning the user that a required field must be filled up with the message displaying next to that field.
With the script, you could click Next without completing a required field and it will go to the next page.
You could even click submit and your data will submit without being asked to complete required fields.
What am I doing wrong?
<script type="text/javascript">
$(document).ready(function () {
$("#msform").validate({
rules: {
certsel: "required",
ssn1: "required",
ssn2: "required",
ssn3: "required",
fname: "required",
lname: "required",
email: {
required: true,
email: true
},
address: "required",
city: "required",
county: "required",
state: "required",
zip: "required",
birthmon: "required",
birthday: "required",
birthyr: "required",
ed: "required",
ref1name: "required",
ref1loc: "required",
ref1title: "required",
ref1area: "required",
ref1pre: "required",
ref1suff: "required",
ref2name: "required",
ref2loc: "required",
ref2title: "required",
ref2area: "required",
ref2pre: "required",
ref2suff: "required",
ref3name: "required",
ref3loc: "required",
ref3title: "required",
ref3area: "required",
ref3pre: "required",
ref3suff: "required",
convictions: "required",
txtCaptcha: "required",
nmon: "required",
nday: "required",
nyr: "required",
fullname: "required"
}
},
messages: {
certsel: "Please select the position for which you're applyingd.",
ssn1: "Please enter your complete Social Security Number.",
ssn2: "Please enter phone number.",
ssn3: "Please enter your name.",
fname: "Please enter your first and last names.",
lname: "Please enter your first and last names.",
email: "Please enter your email address.",
address: "Please enter your complete Address, including city, state and zip code.",
city: "Please enter your complete Address, including city, state and zip code.",
county: "Please enter your complete Address, including city, state and zip code.",
state: "Please enter your complete Address, including city, state and zip code.",
zip: "Please enter your complete Address, including city, state and zip code.",
birthmon: "Please enter your birth month, day and year.",
birthday: "Please enter your birth month, day and year.",
birthyr: "Please enter your birth month, day and year.",
ed: "Please enter your highest level of education or if you have a GED.",
ref1name: "Please enter all information for refrence 1.",
ref1loc: "Please enter all information for refrence 1.",
ref1title: "Please enter all information for refrence 1.",
ref1area: "Please enter all information for refrence 1.",
ref1pre: "Please enter all information for refrence 1.",
ref1suff: "Please enter all information for refrence 1.",
ref2name: "Please enter all information for refrence 2.",
ref2loc: "Please enter all information for refrence 2.",
ref2title: "Please enter all information for refrence 2.",
ref2area: "Please enter all information for refrence 2.",
ref2pre: "Please enter all information for refrence 2.",
ref2suff: "Please enter all information for refrence 2.",
ref3name: "Please enter all information for refrence 3.",
ref3loc: "Please enter all information for refrence 3.",
ref3title: "Please enter all information for refrence 3.",
ref3area: "Please enter all information for refrence 3.",
ref3pre: "Please enter all information for refrence 3.",
ref3suff: "Please enter all information for refrence 3.",
convictions: "Please indicate whether you have had any convictions.",
txtCaptcha: "Please enter the code on above.",
nmon: "Please enter today's date and your full name in the space provided.",
nday: "Please enter today's date and your full name in the space provided.",
nyr: "Please enter today's date and your full name in the space provided.",
fullname: "Please enter today's date and your full name in the space provided."
}
});
});
if ((!$('#msform').valid())) {
return false;
}
</script>
modified 26-Apr-19 11:04am.
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Have you checked that both jQuery and the jQuery Validation scripts are included before this script block?
Have you checked that the <form> element's id is set to "msform"?
Are there any script errors in the browser's developer console?
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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I am so sorry Richard,
I always forget to check the browser developer console for info.
I just did now and it turns out that I did not put jquery validate library at the of the page.
I did just that now it works, sort of.
It displays all the messages before user has a chance to invoke.
We would prefer that the textboxes look normal until user skips required field.
Many thanks for your prompt response as usual.
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samflex wrote: It displays all the messages before user has a chance to invoke.
Probably because you're calling the .valid function immediately, rather than waiting until the form is submitted. 
<script>
...
if ((!$('#msform').valid())) {
return false;
}
</script>
Those lines should probably be inside a handler for the form's submit event:
$("#msform").sumbit(function(evt){
if (!$(this).valid()) {
evt.preventDefault();
}
});
However, I think the jQuery validation library already handles this for you, so they may not be required at all.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Now it works perfectly!
Thank you very sir for always coming to the rescue.
Much appreciated.
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How to create edit button to table that is being created dynamically so as to edit the row of a table.
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Create the button as part of the row and have within the buttons attributes appropriate references to it's particular content.
This is a very important technique and I suggest strongly you master the concept of creating references to items concurrently with creating the item.
| Ravings en masse^ |
|---|
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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<html>
<head>
<meta charset="UTF-8">
</head>
<body id="body">
<div id="wrapper">
<table align='center' cellspacing=1 cellpadding=1 id="mytable" border=1>
<thead>
<tr>
<th>Name</th>
<th>Type</th>
<th>Action</th>
</tr>
</thead>
<tbody id="tbody">
</tbody>
</table>
</div>
<button onclick='display()'> Display</button>
<!--<script src="get-text.js"></script>-->
</body>
</html>
<script>
var myArray = [{ "name": "aaa", "level": "A" }, { "name": "bbb", "level": "B" }, { "name": "ccc", "level": "C" }];
function display() {
var length = myArray.length;
var htmltext = "";
for (var i = 0; i < length; i++) {
console.log(myArray[i]);
htmltext += "<tr id='table"+i+"'><td>"
+myArray[i].name+
"</td><td>"
+myArray[i].level+
"</td><td><button onclick='edit("+i+")'>Edit</button><button onclick='remove("+i+")'>Remove</button></td></tr>";
}
document.getElementById("tbody").innerHTML = htmltext;
}
function edit(indice) {
var htmltext = "<tr><td><input id='inputname"+indice+"' type='text' value='"
+myArray[indice].name+
"'></td><td><input id='inputlevel"+indice+"' type='text' value='"
+myArray[indice].level+
"'></td><td><button onclick='save("+indice+")'>Save</button><button onclick='remove("+indice+")'>Remove</button></td></tr>";
document.getElementById("table"+indice).innerHTML = htmltext;
}
function save(indice) {
myArray[indice].name = document.getElementById("inputname"+indice).value;
myArray[indice].level = document.getElementById("inputlevel"+indice).value;
var htmltext = "<tr id='table"+indice+"'><td>"
+myArray[indice].name+
"</td><td>"
+myArray[indice].level+
"</td><td><button onclick='edit("
+indice+")'>Edit</button><button onclick='remove("
+indice+")'>Remove</button></td></tr>";
document.getElementById("table"+indice).innerHTML = htmltext;
}
function remove(indice) {
console.log(myArray);
myArray.splice(indice, 1);
display();
}
</script>
modified 6-Nov-19 2:31am.
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