Develop Reference

Spreadsheet formula and result in single text input

I have been searching for a way to type a formula into a single text input and when I hit the Enter key, the formula executes and the result replaces the formula in the same input box.
Really I want it to function exactly like an Excel cell. https://formulajs.info/functions/ does what I want, except there is a button to click and the result comes back in a separate input box.
I'm learning to write code, so I don't have the skills to reverse-engineer that plugin, and that was the only thing I could find online that was even close. Most of my searches just keep turning up grid spreadsheets with formulas and it is important for me to keep it to a single input.
Does anyone have any ideas of where I might find something already made or how I could make something like that for myself? I don't need all the fancy engineering, financial, etc types. I just want simple math with an option for parentheses to nest formulas, ie 2*6+(8/4) gives a result of 14.

You can try this for simple JavaScript
const input = document.getElementById('formulaInput');
input.addEventListener('keydown', (event) => {
if (event.keyCode === 13) { // Enter key Code
const formula = input.value;
const result = eval(formula);
input.value = result;
}
});

How to swap two numbers using javascript function with one parameter

My Requirement is
I want to display this output when I gave a(0) the output should come 5 and when I gave a(5) the output should come 0.
a(0) = 5
a(5) = 0
like this
Hint:
Using this function
function A(num){}
like this
Please Help me how to do this I'm new in JS
Please give me different kind of solutions its more useful to my career.

function swap (input) {
if( input == 0)
return 5;
return 0;
}
i think there is no description needed

I think I see what you are getting at.
You want to input one variable into a function, and return another variable that is not defined yet. Then you want to define that variable by inputting it into the same function, and get the first input as the output. And so you should end up with 2 outputs.
Now this is technically impossible, because there are undefined variables at play. However, programming is about imagination and I think I have a solution (it's technically a hack but it will work):
var i = 1;
var output1;
var output2;
function swap(input) {
function func1(input) {
output2 = input;
i++;
}
function func2(input) {
output1 = input;
i = 1;
alert(String(output1) + "\n" + String(output2));
}
if (i === 1) {
func1(input);
}
else if (i === 2) {
func2(input);
}
}
while(true) {
swap(prompt("Enter your first input (this will be your second output):"));
swap(prompt("Enter your second input (this will be your first output):"));
}
The swap function goes back and forth between the values 1 and 2 in the variable i. That is how it keeps track of first or second inputs and their exact opposite outputs. The input, or parameter of the swap function is whatever the user types into the prompt boxes. Feel free to make it user-friendly, this is just the dirty code behind it. The reason they are outputted together is because the second input is undefined, and so the machine cannot guess what you were going to input. So first my little program collects all the data and just reverses the order when it is time to output. But to the user who knows nothing about JavaScript and what is going on underneath the hood, this would work perfectly in my opinion.
This should work for any data types inputted, I tested it myself with objects, strings, numbers, and arrays. Hope this helps!!

Shorter alternative to #mtizziani's answer:
let swap = x => !x * 5 // yes this is all
console.log(swap(0));
console.log(swap(5));
We toggle the input, so x is now 1 or 0
We multiple by 5.
Job done.

Why aren't these two strings the same?

I'm trying to write some javascript and get some elements by using document.getElementById("ct100_ContentPlaceHolder1_search"); and for some reason it wouldn't find it. It would always return null.
After playing around thinking it was my use of double quotes or single quotes, I found the element's id in the document, and printed the id to a textbox. I copy/pasted the text to notepad and then decided to write this little bit of code
var id = e.target.id;
if (id == "ctl00_ContentPlaceHolder1_search") { <-- Copied/pasted from notepad. Returns true
var foo6 = document.getElementById("ctl00_ContentPlaceHolder1_search");
}
if (id == "ct100_ContentPlaceHolder1_search") { <-- Typed out. Returns false
var foo5 = document.getElementById("ct100_ContentPlaceHolder1_search");
}
The page is being built with ASP.NET if that matters at all. So what's going in? I haven't got a clue.
Here's a regexr I made to show the two strings aren't the same. The regular expression is the copied/pasted from notepad. It shows that the '1' is different, but what kind of '1' is that?

The first string has a lower-case L in ctl.
The second has the number 1 in ct1.

jquery masked input plugin to not clear field when errored

I'm looking at the http://digitalbush.com/projects/masked-input-plugin/
I'm calling it like this:
$(control).mask('999-999-9999');
And I don't want it to throw away the users input if something is wrong, e.g. they haven't finished
[407-555-____]
If you leave the field after having typed this much, it clears it. I'd like to leave it so they can finish later.
I'm new to jQuery, and I've looked through his source, but I can't find any way to do that, nor can I find any way to edit it to accomplish what I want, because the code is arcane to my eyes.

Set autoclear option to false.
$(control).mask('999-999-9999', {autoclear: false});

It looks like I should just make the whole mask optional:
mask('?999-999-9999')
That way the control thinks what the user has is "valid" and I can continue. Even though it isn't really the optional part of the mask.

You should delete statement input.val(""); in checkVal() function for a proper solution.
If you're using minified version, you should search and delete statement:
if(!a&&c+1<i)f.val(""),t(0,k);else

Try update file jquery.maskedinput.js
In function function checkVal(allow) set parameter allow on true. Its help for me.
function checkVal(allow) {
allow = true; ///add this command
//..............
}

In addition to removing the input.val("") in checkVal() you can also change the call to clearBuffer.
In the original code it is: clearBuffer(0, len); removing all user input.
if you change this to clearBuffer(lastMatch + 1, len); the user input will be displayed, followed by the mask placeholders that are still needed to complete correct input.
I have also added a user message in the .bind. This works for us, as we are using the MaskedInput for exactly one type of input. I'm checking for any input going further than position 7, because that's where the user input starts.
Here is what I did:
.bind("blur.mask", function() {
// find out at which position the checkVal took place
var pos = checkVal();
// if there was no input, ignore
if (pos <=7) {input.val(""); clearBuffer(0, len);}
// if the user started to input something, which is not complete, issue an alert
if (pos > 7 && pos < partialPosition) alert("Tell the user what he needs to do.");
if (input.val() != focusText)
input.change();
})

Adding Placeholder could solve the problem.
$(control).mask('999-999-9999');
Add an empty place holder into mask. see below
$(control).mask('999-999-9999', { placeholder: "" });
which would replace _ on the input text field by default. so there would bot be any _ left if the input length is dynamic and not fixed.

Looking for into the pluging script the unmask method.
$('#checkbox').unmask();

How can I ensure that changes to a form DOM are complete before POSTing?

Currently I have a race condition existing in my JavaScript code. What I am trying to do with this code is convert all check boxes which are a part of the 'checkbox' class and are not checked into text boxes with a value of zero. Currently when you post a check box that is not checked it does not appear in the $_POST data. However I need to know all the values whether true or false for these particular set of check boxes.
The code I have is here:
Code:
function checkboxConvert() {
var chkBxs = $$('.checkbox');
for (var i = 0; i < chkBxs.length; i++) {
if (chkBxs[i].checked == false) {
chkBxs[i].type = 'textbox';
chkBxs[i].value = '0';
}
}
setTimeout("document.productForm.submit();",1000);
}
Now the problem that I have been getting is that when I try to submit this form the values of the recently changed text boxes does not appear in the $_POST data. Therefore, as you can see above I have postponed the page submit for 1 sec and then I have all the data available to me. However as time goes on and my data set gets larger, 1 sec may no longer be enough. This I think is a race condition and I need to figure some way of running the code only after all the check boxes have been converted and they have their new values. I would have thought that this would be unnecessary from the start, but for some reason it's trying to run both pieces simultaneously and I can't submit until I have the proper values in place.
Any help is much appreciated!

This is definitely not the way to do web. I strongly advise you abandon your checkboxConvert function, and solve this issue on the server side

JavaScript always runs single-threaded in the browser so I don't think it can be a race condition.

I'd generally agree with others that you shouldn't do this, but your problem may be that you're changing the element to a type of "textbox" instead of "text". If you declare an input of type "textbox" in HTML markup, it will usually render as a text field anyway because that's the default. However, changing an already valid "checkbox" type input to the invalid "textbox" may not work predictably.
Try changing it to this:
function checkboxConvert() {
var chkBxs = $$('.checkbox');
for (var i = 0; i < chkBxs.length; i++) {
if (chkBxs[i].checked == false) {
chkBxs[i].type = 'text';
chkBxs[i].value = '0';
}
}
// Because JS in the browser is single-threaded, this
// cannot execute before the preceding loop completes anyway.
document.productForm.submit();
}

There's got to be a better way to do this. Try something like:
Know about all your possible values on the server side. It looks like you're using PHP; keep a simple array with the names of your checkboxes.
When you take your $_POST data, remove the names of checkboxes you've received values for from your array.
The remaining are all false.