So I've written a web page with a few JavaScript functions.
The page runs perfectly in Dreamweaver but when I tried it out in a browser (Google Chrome and Firefox) the JavaScript flashes for a split second then clears. I have no idea at all why this is.
<body>
<form name="myForm">
<ol>
<li>
<h1> TILE CALCULATOR</h1>
</li>
<li>
<label for="wall height">Wall height (cm)</label>
<input type="text" id="wall_height" />
</li>
<li>
<label for="wall width">Wall Width (cm)</label>
<input type="text" id="wall_width" />
</li>
<li>
<label for="tile height">Tile Height (cm)</label>
<input type="text" id="tile_height" />
</li>
<li>
<label for="tile width">Tile Width (cm)</label>
<input type="text" id="tile_width" />
</li>
<button onclick="javascript:validate();"> Calculate </button>
</ol>
</form>
<br />
<p id="result"></p>
<br />
<canvas id="myCanvas">
Your browser does not support this feature</canvas>
<br />
<br />
<script language="javascript" type="text/javascript">
//functoin to validate the inputs by the user
//user can only enter a number and all fields must be filled
function validate()
{
//first make sure canvas is clear
clearCanvas()
//take the inputs as variables
var x = document.getElementById("tile_width").value;
var y = document.getElementById("tile_height").value;
var z = document.getElementById("wall_width").value;
var i = document.getElementById("wall_height").value;
//check if the user has entered nothing and alert if they have
if (x==null || x=="" || y==null || y=="" || z==null || z=="" || i==null || i=="")
{
alert("All the fields have to be filled out!");
clearResult();
}
// check if the user has entered invalid values, only numbers can be entered
if (isNaN(x) == true || isNaN(y) == true || isNaN(z) == true || isNaN(i) == true)
{
alert("Dimensions can only be numbers!");
clearResult();
}
//check for negatives
if (x <= 0 || y <= 0 || z <= 0 || i <= 0)
{
alert("invalid dimension input, positive non-zero values only");
clearResult();
}
//if valid calculate tiles and print
else
tileCalculator();
}
function tileCalculator()
{
//take the input as variables
var tileWidth = document.getElementById("tile_width").value;
var tileHeight = document.getElementById("tile_height").value;
var wallWidth = document.getElementById("wall_width").value;
var wallHeight = document.getElementById("wall_height").value;
//find the areas of the tile and the wall
var tileArea = tileWidth * tileHeight;
var wallArea = wallWidth * wallHeight;
//divide these to find the number of tiles needed
var noOfTiles = (wallArea/tileArea);
//prints the result of noOfTiles
document.getElementById("result").innerHTML=" The number of Tiles you will need are : " + noOfTiles;
//scalled tiles to the canvas width of your choice
var scalledWidth = 500;
var ratioHW = wallHeight/wallWidth;
var scalledHeight = ratioHW*scalledWidth;
//scaled tile sizes
//scale the tiles to correct pixels
var scalledTileWidth = (tileWidth/wallWidth)*scalledWidth;
var scalledTileHeight = (tileHeight/wallHeight)*300;
//finds the number of tiles needs in a row
var noWidth = wallWidth/tileWidth;
//number of tiles in a column
var noHeight = wallHeight/tileHeight;
var canvas = document.getElementById("myCanvas");
canvas.style.width=scalledWidth + "px";
canvas.style.height=scalledHeight + "px";
printWall(0,0,noWidth,scalledTileWidth,(scalledTileHeight/2),noHeight);
}
//print a tile given the position and dimensions
function printTile(x,y,tileWidth,tileHeight)
{
var c=document.getElementById("myCanvas");
var ctx=c.getContext("2d");
ctx.fillRect(x,y,tileWidth,tileHeight);
}
//prints one row of tiles given the starting position and number to be printed
function printTileRow(x,y,numberOfTiles,tileWidth,tileHeight)
{
var start = 0;
//loops upto number of tiles in a row
while (start < numberOfTiles)
{
//prints a tile each time
printTile(x,y,tileWidth,tileHeight);
//next brick position
x = x + (tileWidth + 1); // add a space between tiles here.
start++;
}
}
//prints the wall
function printWall(x,y,numberOfTiles,tileWidth,tileHeight,numberOfRows)
{
//holds whether last row was shifted
var shiftCount = 0;
//starting index
var start = 0;
//loop up adding a row until required number of rows
while (start < numberOfRows)
{
//prints half a tile at the start of each row
printTile(0,y,(0.5 * tileWidth - 1),(tileHeight));
//prints the row
printTileRow((x+shiftCount),y,numberOfTiles,tileWidth,tileHeight);
//if shifted
if (shiftCount > 0)
{
//was shifted last row
shiftCount = 0;
}
else
{
//was not shifted last row
shiftCount = shiftCount + (0.5*tileWidth);
}
start++;
//start next row
y = y + (tileHeight + 1);
}
}
//clears the canvus each time the button is pressed
function clearCanvas()
{
//reset canvus to 300 by 300 and clear
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext('2d');
canvas.style.height="300px";
canvas.style.width="300px";
context.clearRect(0,0,300,300);
}
function clearResult()
{
document.getElementById("result").innerHTML="";
}
</script>
</body>
I would really appreciate it if someone could have a quick look for me! Thanks,
Try using onclick="javascript:validate();" on the form tag instead of on the button tag and try using 'onsubmit' instead of 'onclick'
Just replace your onclick attribute by onclick='validate(); return false'.
OR (better then previous)
Just add a type="button" attribute to your button tag, once the HTML5 button's default behavior is to submit forms.
Useful tip
Bind your handler programatically, this way (with no jQuery):
<button type="button" id="calculate"> Calculate </button>
...
window.addEventListener("load", function(){
document.getElementById("calculate").addEventListener("click", validate);
});
there is no problem with kepping the button in the form you you need to return false everytime to avoid the form submit using the return false like this
onclick="javascript:validate();return false;"
Related
What I want is, after the user enters the number of subjects, the system will show the number of input box according to the number of subjects entered, then when the user clicks on the button, it should show the sum. I tried many ways, but I failed to show the sum, anyone knows what is the mistake I made?
Below is my code:
function select() {
var x = parseInt(document.getElementById('1').value);
if (document.getElementById('1').value == "") {
alert("Please fill up number of subject");
} else if (isNaN(x) == true) {
alert("Please fill up number of subject with number");
} else {
var subject = parseInt(document.getElementById('1').value);
var sum = 0;
for (var num = 1; num <= subject; num++) {
document.write("Enter the mark for subject " + num + " : ");
var value = parseFloat(document.write("<input/><br>"));
sum += value;
}
var calc = document.write("<button>Next</button><br>");
calc.onclick = function() {
next()
};
function next() {
document.write("Total marks: " + sum + "%");
}
}
}
<html>
<body>
Enter the number of subject: <input type="text" onkeypress="return/[0-9]/i.test(event.key)" id="1" value=""><br>
<button onclick="select()">Check</button><br>
</body>
</html>
That's how I have rewritten a big part of your code. I have place inline comments to explain what I do.
function select() {
var x = parseInt(document.getElementById('1').value, 10);
// Getting the div that wraps the initial form.
var formWrapper = document.querySelector('.formWrapper');
// Getting the div, that is going to display the new fields and the results.
var results = document.querySelector('.results');
// I have switch your statement from x == '' to '' === x as it
// consists a good practice
if ( '' === x ) {
alert("Please fill up number of subject");
// I have remove the isNaN(x) == true, because the isNan will
// be either true or false.
} else if ( isNaN(x) ) {
alert("Please fill up number of subject with number");
} else {
// Using parseInt(x, 10) to set the base.
var subject = parseInt(x, 10);
// In this array, I store the auto-generated fields.
var fieldsList = [];
// Removing the first div from the DOM
formWrapper.parentElement.removeChild(formWrapper);
for ( var num = 1; num <= subject; num++ ) {
// I am creating a new field
var newField = document.createElement('input');
// I push the field into the array I made for the fields.
fieldsList.push(newField);
// I append the field in the HTML
results.appendChild(newField);
// I create a <br> tag
var br = document.createElement('br');
// And I append the tag in the DOM
results.appendChild(br);
}
// I create the button that is going to handle the Next functionality
var nextButton = document.createElement('button');
// I set the button text
nextButton.innerText = 'Next';
// I add an Event Listener for the click event.
nextButton.addEventListener(
'click',
function() {
// I reset the sum to 0
var sum = 0;
// I itterate the fields auto-generated and saved in the array
fieldsList.forEach(
function(field) {
// I get the value
sum += parseInt(field.value, 10);
}
);
// I create the field that is going to display the output
let resultText = document.createElement('div');
// I set the text based on the sum
resultText.innerText = "Total marks: " + sum + "%";
// I append the text message to the DOM
results.appendChild(resultText);
}
);
// I append the button to the DOM
results.appendChild(nextButton);
}
}
<html>
<body>
<div class="formWrapper">
Enter the number of subject: <input type="text" onkeypress="return/[0-9]/i.test(event.key)" id="1" value=""><br>
<button onclick="select()">Check</button><br>
</div>
<div class="results"></div>
</body>
</html>
I'm working on a poject, need it must be auto calculation.
let say that we have uncounted hidden inputs with known same class and attr. diffrent value, attr diffrent price, price2 price 3 in a div to count
What im trying to do is to get attrs (price, priceX2, priceX3)
if the user inserted a number ex. 1 or 40, will return first input(price, priceX2, priceX3), and if its given 61 0r 70 then it will return to the third input(price, priceX2, priceX3) so on
<div id="countDiv">
<input type="number" value="" id="counter" />
<button id="countBtn"> Count </button>
<input type="hidden" value="40" price="1100" priceX2="1200" priceX3="1220" class="classeid">
<input type="hidden" value="60" price="1150" priceX2="1250" priceX3="1300" class="classeid">
<input type="hidden" value="70" price="1220" priceX2="1350" priceX3="1400" class="classeid">
</div>
<script>
$(document).ready(function(){
$("#countBtn").click(function(){
var parentDOM = document.getElementById("countDiv");
var classCounter = parentDOM.getElementsByClassName("classeid");
var counter = $("#counter").val();
for (var i = 0, n = classCounter.length; i < n; ++i) {
var mPrice = parseInt(classCounter[i].value);
var cPrice = parseInt(classCounter[i].getAttribute('price'));
var cPriceX2 = parseInt(classCounter[i].getAttribute('priceX2'));
var cPriceX3 = parseInt(classCounter[i].getAttribute('priceX3'));
}
});
});
</script>
Hope this code help you.
Do do it dynamically it's not better to do using the Hidden field if you have more than 3 input hidden field. The logic will be different in that case.
Considering only 3 hidden input fields then code looks as below:
HTML Code:
provide id to the each hidden input fields as first, second and third as written in the code.
JavaScript Code:
$("#countBtn").click(function(){
var counter = $("#counter").val();
if(counter > 0 && counter <= 40) {
var mprice = $("#first").val();
var cprice = $("#first").attr("price");
var cPriceX2 = $("#first").val("priceX2");
var cPriceX3 = $("#first").attr("priceX3");
}
else if(counter > 39 && counter <= 60) {
var mprice = $("#second").val();
var cprice = $("#second").attr("price");
var cPriceX2 = $("#second").val("priceX2");
var cPriceX3 = $("#second").attr("priceX3");
}
else {
var mprice = $("#third").val();
var cprice = $("#third").attr("price");
var cPriceX2 = $("#third").val("priceX2");
var cPriceX3 = $("#third").attr("priceX3");
}
}
So I am currently programming my very first website. I am using pure javascript. A part of it will be a comments section - which are stored in a SQL- Database on the server. I want comments to have a maximum length. After searching the web I found this solution. Please do note that this solution is far from perfect.
var maxchar = 160;
var i = document.getElementById("textinput");
var c = document.getElementById("count");
c.innerHTML = maxchar;
i.addEventListener("keydown", count);
function count(e) {
var len = i.value.length;
if (len >= maxchar) {
e.preventDefault();
} else {
c.innerHTML = maxchar - len - 1;
}
}
textarea {
display: block;
width: 200px;
height: 100px;
}
Remaining characters: <span id="count"></span>
<textarea id="textinput">
</textarea>
I found a lot of similar solutions also using jQuery. Now this solution has two major flaws. First it counts the characters before the new character is entered since the registered event is the keydown event - value.length will always give the old count. Secondly once you hit the maximum amount of characters it will prevent all user input - there is no way to delete characters anymore.
Registering the count to keyup doesn't help either - it can't prevent the input of the keydown event.
What is a better solution than this?
So after playing around with it for a bit I came up with this solution. The trick is to split up the count function into two parts - one which counts the characters and one which prevents the user input. Register the preventInput() on keydown, such that the input is prevented before entering, and register the count() on keyup, such that the new value of length is used in the function.
function preventInput(event) {
if (event.target.id == 'commentText')
var maxchar = 255;
else
var maxchar = 20;
//I'm using target here, such that I can use this as a callback for different textfields
var len = event.target.value.length;
var key = event.keyCode || event.which;
//prevent every input apart from UP, DOWN, LEFT, RIGHT and BACKSPACE
if (len >= maxchar && (key != 8 && !(key >= 37 && key <= 40)))
event.preventDefault();
}
function count(event) {
//different lengths for different textfields
if (event.target.id == 'commentText')
var maxchar = 255;
else
var maxchar = 20;
var len = event.target.value.length;
//setting the remaining chars field depending whether Author or Text triggered the event
document.getElementById("remain" + event.target.id.split('comment')[1]).innerHTML = 'Remaining characters:' + (maxchar - len);
//disable the submit button when the user entered too many chars (CTRL + V)
var btn = document.getElementById("submitBtn");
if (len > maxchar)
btn.disabled = true;
else
btn.disabled = false;
}
function setup() {
//setting to events
document.getElementById("commentAuthor").addEventListener("keydown", preventInput);
document.getElementById("commentAuthor").addEventListener("keyup", count);
document.getElementById("commentText").addEventListener("keydown", preventInput);
document.getElementById("commentText").addEventListener("keyup", count);
//initial count
document.getElementById("remainAuthor").innerHTML += 20;
document.getElementById("remainText").innerHTML += 255;
}
.charCounter {
opacity: 0.4;
}
<body onload="setup()">
<form>
<fieldset style="display: inline-block;">
<legend>Submit a comment</legend>
Name:
<input type="text" id="commentAuthor" name="Name:">
<div class="charCounter" id="remainAuthor">Remaining characters:</div>
<textarea name="comment" id="commentText" rows="4" cols="100"></textarea>
<div class="charCounter" id="remainText">Remaining characters:</div>
<br>
<input type="submit" id="submitBtn" value="Submit Comment!">
</fieldset>
</form>
</body>
You can modify the first snipped into something like this
var maxchar = 160;
var i = document.getElementById("commentText");
var c = document.getElementById("remainText");
c.innerHTML = maxchar;
i.addEventListener("keydown", count);
function count(e) {
var len = i.value.length;
len >= maxchar ? i.value = i.value.slice(0,len-1) : c.innerHTML = maxchar - len - 1;
}
<body onload="setup()">
<form>
<fieldset style="display: inline-block;">
<legend>Submit a comment</legend>
Name:
<input type="text" id="commentAuthor" name="Name:">
<div class="charCounter" id="remainAuthor">Remaining characters:</div>
<textarea name="comment" id="commentText" rows="4" cols="100"></textarea>
<div class="charCounter" id="remainText">Remaining characters:</div>
<br>
<input type="submit" id="submitBtn" value="Submit Comment!">
</fieldset>
</form>
</body>
I am trying to perform calculation using JavaScript. When user enter less than 10 pages in input (#page) the cost is 1. if he adds more than 10, each page costs .10. there are 2 options for checkbox, if he clicks first checkbox 10 is added and second checkbox 15 is added.
This is working when it is done in sequential steps. (input then clicking checkbox).
Ex: Input is : 9 (total: 1)
click checkbox1 - duplicates (total : 11)
click checkbox1 - laser (total: 26)
Now if i change the Input to 11, then the total becomes 1.10 - even if both the checkboxes are checked.. (expected result should be - 26.10)
I am not sure how to do this...can anyone help me out
<html>
<head>
<title>Calculation</title>
<script>
function calculate() {
var pages=document.getElementById("page").value;
if(pages <=10) {
total.value=1;
}
if(pages >= 11) {
var extra_pages= pages - 10;
var new_total= extra_pages * .10;
var new_total1= 1 + new_total;
total.value= new_total1;
}
}
function checkbox1() {
if(document.getElementById("ckbox1").checked === true) {
var total1=document.getElementById("total").value;
const add1 = 10;
var check1 = +total1 + +add1;
total.value=check1;
}
if(document.getElementById("ckbox1").checked === false) {
var total1=document.getElementById("total").value;
const sub1 = 10;
var check2 = +total1 - +sub1;
total.value = check2;
}
}
function checkbox2() {
if(document.getElementById("ckbox2").checked === true) {
var total1=document.getElementById("total").value;
const add1 = 15;
var check1 = +total1 + +add1;
total.value=check1;
}
if(document.getElementById("ckbox2").checked === false) {
var total1=document.getElementById("total").value;
const sub1 = 15;
var check2 = +total1 - +sub1;
total.value = check2;
}
}
</script>
<body>
Enter a Number: <input type="text" id="page" value="1" oninput="calculate()">
<br>
<br><br><br><br>
duplicates <input type="checkbox" id="ckbox1" onclick="checkbox1()">
laser print: <input type="checkbox" id="ckbox2" onclick="checkbox2()"> <br><br>
Total: <input type="text" id="total">
</body>
</html>
You can use calculate for all changes instead of creating each one for each input, which makes the calculation complex.
// Get reference to inputs.
var page = document.getElementById("page");
var total = document.getElementById("total");
var dup = document.getElementById("ckbox1");
var laser = document.getElementById("ckbox2");
function calculate() {
// To Number
var pages = parseInt(page.value, 10);
var value = 0;
if (pages <= 10) {
value = 1;
} else {
var extra_pages = pages - 10;
var new_total = extra_pages * .10;
var new_total1 = 1 + new_total;
value = new_total1;
}
// Add 10 if dup is checked.
if (dup.checked) {
value += 10;
}
// Add 15 if laser is checked.
// These can be moved out like
// const laserVal = 15;
// value += laserVal if you don't want magic number here.
if (laser.checked) {
value += 15;
}
// Truncate float.
total.value = value.toFixed(1);
}
Enter a Number:
<input type="text" id="page" value="1" oninput="calculate()">
<br>
<br>
<br>
<br>
<br>
duplicates:<input type="checkbox" id="ckbox1" onclick="calculate()">
laser print:<input type="checkbox" id="ckbox2" onclick="calculate()">
<br>
<br>Total:
<input type="text" id="total">
Hi I'm new to javascript and I would like you to help me figure out why I can't get the result of the random number generator to appear in the span tag after the user clicks a calculate button using the min and max number they entered. I believe there is nothing wrong with the random number function it's just when I want to use the random number function as an event handler for the onclick event for the button it doesn't work. well, what I did was, I made a function called answer to gather the users input and to use that input as a parameter for the the random number function that is being called inside the answer function.
Then I used the answer function as an event handler for the onclick thinking that it would have the result of the the random number generator and would apply that to the onclick. and I stored that in var called storage so I could place the result of the event in the span tag later.
Here is the js fiddle of the code. can you help me solve my problem by getting the result of the random_number function in to the span $("output") after the button $("calculate") click?
only pure javascript, no jquery please.
Thank you in advance for your help. and I'm sorry if I got terminology wrong and for bad spelling. http://jsfiddle.net/jack2ky/WDyMd/
<label for="min">Enter the min:</label>
<input type="text" id = "min" /> <br />
<label for="max">Enter the max:</label>
<input type="text" id = "max" /> <br />
<input type="button" id = "calculate" value = "calculate"/>
<span id ="output"> </span>
<script>
var $ = function(id){
return document.getElementById(id);
}
window.onload = function () {
var random_number = function(min, max, digits){
digits = isNaN(digits) ? 0 : parseInt(digits);
if(digits < 0){
digits = 0;
}else if (digits > 16){
digits = 16
}
if(digits == 0){
return Math.floor(Math.random() * (max - min +1)) +min;
}else {
var rand = Math.random() * (max - min) + min;
return parseFloat(rand.toFixed(digits));
}
}
var storage = $("calculate").onclick = answer;
var answer = function(){
var miny = $("min").value;
var maxy = $("max").value;
return random_number(miny, maxy);
}
$("output").firstChild.nodeValue = storage;
}
</script>
</body>
</html>
var storage = $("calculate").onclick = answer;
...
$("output").firstChild.nodeValue = storage;
These two statements are called on page load. What is happening is you are changing the value of variable storage but the statement var storage = $("calculate").onclick = answer;
is being called only once when the page loads. You need to update the answer when user clicks the button. So you can remove $("output").firstChild.nodeValue = storage; and update the answer function like:
var answer = function(){
var miny = parseInt( $("min").value );
var maxy = parseInt( $("max").value );
var ans = random_number(miny, maxy);
$("output").innerHTML = ans;
}
This should do it:
<!DOCTYPE html>
<html>
<head>
<script>
var $ = function(id){
return document.getElementById(id);
}
window.onload = function () {
var random_number = function(min, max, digits){
digits = isNaN(digits) ? 0 : parseInt(digits);
if(digits < 0){
digits = 0;
}else if (digits > 16){
digits = 16
}
if(digits == 0){
return Math.floor(Math.random() * (max - min +1)) +min;
}else {
var rand = Math.random() * (max - min) + min;
return parseFloat(rand.toFixed(digits));
}
}
$("calculate").onclick = function() {
var miny = $("min").value;
var maxy = $("max").value;
$("output").firstChild.nodeValue = random_number(miny, maxy);
}
}
</script>
</head>
<body>
<label for="min">Enter the min:</label>
<input type="text" id = "min" /> <br />
<label for="max">Enter the max:</label>
<input type="text" id = "max" /> <br />
<input type="button" id = "calculate" value = "calculate"/>
<span id ="output"> </span>
</body>
</html>
$("output").firstChild.nodeValue = storage;
This line seems to be the problem because your output-Element has no firstChild. So the value gets written nowhere.
Just use
> $("output").nodeValue = storage;
edit: Tested this in jsFiddle - this is not the solutions as mentioned below!
If You are able to get your value in the variable storage
then you can simply render this value in span as HTML
$("#output span").html = storage;