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I want to load a png image in base64 to html5 canvas element. I have this code:
<html>
<head></head>
<body>
<canvas id="pageCanvas"></canvas>
<script type="text/javascript">
var canvas = document.getElementById("pageCanvas");
var ctx = canvas.getContext("2d");
var imageData ="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAIAAAACDbGyAAAAAXNSR0IArs4c6QAAAAlwSFlzAAALEwAACxMBAJqcGAAAAAd0SU1FB9oMCRUiMrIBQVkAAAAZdEVYdENvbW1lbnQAQ3JlYXRlZCB3aXRoIEdJTVBXgQ4XAAAADElEQVQI12NgoC4AAABQAAEiE+h1AAAAAElFTkSuQmCC";
var imageObj = new Image();
imageObj.src = imageData;
ctx.drawImage(imageObj, 50, 100);
</script>
</body>
</html>
The above code working well in IE, chrome, Microsoft edge. But in Firefox the image was not displayed. It display blank page. Sometime when we reload the page then it displayed an image in canvas.
Best,
Parthi
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I'm doing an assignment with an order form and was wondering if there is a function that will auto fill the cost field after entering the quantity field?
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You really miss the point of having an assignment: you are supposed to figure it out, and in the process, learn!
You may wish to get used to that idea sooner, rather than later, as that's what this business is all about.
Here's something for you to consider that's an important part of figuring out how to answer your question: where is the cost-per-unit data located at the time the quantity is entered? A lot depends upon that.
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein |
| "As far as we know, our computer has never had an undetected error." - Weisert |
| "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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@WW∴ Balboos - forums are for getting help a-hole. if you don't have an answer mind your own business.
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Looks like the OP has been deactivated by the hamsters for his abusive reply.
"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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Yeah - I noticed that when I tried to see what else he's been up to (i.e., aside from trying to get his homework done). I think what was most annoying is that I even gave him some suggestions rather than the tried-and-true "Do Your Own Homework".
Maybe someone can develop a CP-AI that would recognize the new accounts created by those who are thrown out of the hamster cage.
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein |
| "As far as we know, our computer has never had an undetected error." - Weisert |
| "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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W∴ Balboos wrote: I tried to see what else he's been up to
Lots of homework[^] it seems.
"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 still can believe the web runs on it! If there is any proof the devil exists javascript must be it.
It is so easy to make a mistake and not catch it until you are debugging.
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I can understand your frustration. Maybe you want to take a look on TypeScript.
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I've done some typescript and I absolutely love what Anders Hedjelsberg did.
The library I will be using still needs a typescript facade though , so I have to stick with javascript.
I can't help but wonder what were the twisted minds that created this devil-spawn language thinking when they were going through the design process.
modified 28-Oct-15 18:00pm.
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Auto-completion can't do it all.
In a compiled language, the compiler might catch an error - but not a bug.
In a scripted language, you need to run it.
If either of these routes is unsuitable, I would suggest finding an alternate language for your problems.
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein |
| "As far as we know, our computer has never had an undetected error." - Weisert |
| "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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Auto completion can't do it all.
Well , of course not , but it's a great tool when you are learning a new library. Even after you have learned it's a big help.
In a compiled language, the compiler might catch an error - but not a bug.
In a compiled language the compiler will catch all syntax errors.
And it will spot some bugs ( dead code, unused variables , uninitialized variables).
If either of these routes is unsuitable, I would suggest finding an alternate language for your problems.
Of course they don't suite my needs, I'll be using typescript whenever I can unluckily for some cases there is no other choice than using javascript.
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I want to use buttons in tree. So I used the article Working on JSON objects in jQuery and MVC given by Dr. Song Li in 24 Nov 2010. I have taken button instead of textnode. The buttons work fine first time. But these buttons do not fire after addExamBySession or addExamByjson is clicked.
var dateDeserialize = function (dateStr) {
var dt = new Date(parseInt(dateStr.substr(6)));
return prependZero((dt.getMonth() + 1))
+ "/" + prependZero(dt.getDate())
+ "/" + dt.getFullYear()
+ " " + prependZero(dt.getHours())
+ ":" + prependZero(dt.getMinutes())
+ ":" + prependZero(dt.getSeconds());
};
var FixDateinJson = function (JsonStudents) {
$.each(JsonStudents, function (i, JsonStudent) {
$.each(JsonStudent.ClassesTaken, function (i, JsonClass) {
$.each(JsonClass.ExamesTaken, function (i, JsonExam) {
JsonExam.ExamTime = dateDeserialize(JsonExam.ExamTime);
});
});
});
return JsonStudents;
}
var buildStudentTree = function (students) {
var createTextNode = function (text,id) {
var span = document.createElement("span");
span.setAttribute("style", "margin-left: 2px");
($('<input>').attr('type', 'button').attr('id',id)
.attr('value', text)).appendTo(span);
return span;
};
var root = document.createElement("ul");
root.id = "StudentTreeRoot";
root.setAttribute("style", "margin: 15px");
root.className = "filetree";
$.each(students, function (i, student) {
var studentNode = document.createElement("li");
studentNode.className = "closed";
var span = document.createElement("span");
span.className = "folder";
span.appendChild(createTextNode(student.Name, 's'+(i+1)));
studentNode.appendChild(span);
var classesNode = document.createElement("ul");
$.each(student.ClassesTaken, function (j, aClass) {
var classNode = document.createElement("li");
classNode.className = "closed";
span = document.createElement("span");
span.className = "folder";
span.appendChild(createTextNode(aClass.Name, 'c' + (i+1)));
classNode.appendChild(span);
var examesNode = document.createElement("ul");
examesNode.className = "folder";
$.each(aClass.ExamesTaken, function (k, aExam) {
var examNode = document.createElement("li");
examNode.className = "closed";
span = document.createElement("span");
span.className = "folder";
span.appendChild(createTextNode(aExam.Description, 'e' + (i + 1)));
examNode.appendChild(span);
var detailNode = document.createElement("ul");
var examTime = document.createElement("li");
span = document.createElement("span");
span.className = "file";
span.appendChild(createTextNode(aExam.ExamTime,'et'+(i+1)));
examTime.appendChild(span);
detailNode.appendChild(examTime);
var score = document.createElement("li");
span = document.createElement("span");
span.className = "file";
span.appendChild(createTextNode(aExam.Score, 'es'+(i+1)));
score.appendChild(span);
detailNode.appendChild(score);
examNode.appendChild(detailNode);
examesNode.appendChild(examNode);
});
classNode.appendChild(examesNode)
classesNode.appendChild(classNode);
});
studentNode.appendChild(classesNode);
root.appendChild(studentNode);
});
$("#StudentTree").html("").append(root);
$("#StudentTreeRoot").treeview();
};
$(document).ready(function () {
$("#StudentTree").html("");
$.ajax({
cache: false,
type: "POST",
async: false,
url: GetStudentsURL
+ "/?NoOfStudents=" + NoOfStudents
+ "&NoOfClasses=" + NoOfClasses
+ "&NoOfExams=" + NoOfExams,
dataType: "json",
success: function (students) {
StudentJson = FixDateinJson(students);
buildStudentTree(StudentJson);
}
});
$("#btnAddAnExamJson").click(function () {
$("#StudentTree").html("Loading ...");
$.ajax({
cache: false,
type: "POST",
url: AddAnExamByJsonURL,
contentType: 'application/json',
dataType: "json",
data: JSON.stringify(StudentJson),
success: function (students) {
StudentJson = FixDateinJson(students);
buildStudentTree(StudentJson);
}
});
});
$("#btnAddAnExamSession").click(function () {
$("#StudentTree").html("Loading ...");
$.ajax({
cache: false,
type: "POST",
url: AddAnExamBySessionURL,
dataType: "json",
success: function (students) {
StudentJson = FixDateinJson(students);
buildStudentTree(StudentJson);
}
});
});
$("#s1, #s2, #s3, #c1, #c2, #c3, #e1, #e2, #e3").click(function () {
alert($(this).attr('id') + ' Clicked');
$.ajax({
cache: false,
type: "POST",
dataType: "json",
success: function (students) {
StudentJson = FixDateinJson(students);
buildStudentTree(StudentJson);
}
});
});
});
</script>
modified 22-Oct-15 1:18am.
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If you are re-building the DOM then you have to re-attach the jQuery events to the new DOM elements you have created as the events were attached to elements that no longer exist. An alternative is to use "Delegated events" in jquery.
http://api.jquery.com/on/[^]
These won't perform well though.
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Thank You For Your Valuable suggestion. By using bind() function it works correctly.
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Ok I'm just a beginner and have an assignment. We are doing an order form where you add up the product amounts and come up with total cost using parseFloat for decimals. I can get the product amounts in decimals and it adds up right in the total cost, but the total cost does not come up with decimals and I cannot figure out why. Here is my js function code:
function total_price(){
var a = parseFloat(document.order.sub1.value);
var b = parseFloat(document.order.sub2.value);
var c = parseFloat(document.order.sub3.value);
var d = parseFloat(document.order.sub4.value);
var e = parseFloat(document.order.sub5.value);
var f = parseFloat(document.order.sub6.value);
var total = a + b + c + d + e + f;
document.getElementById("total").value = total;
}
This is my input tag (it's inside td tag:
<input class="numbers" id="total" onclick="total_price()" name="total" size="7" />
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If your a,b,c,d,e,f, are integer values then the answer will be formatted as such too. You could try
document.getElementById("total").value = total.toFixed(2);
in the last line to force it to display to 2 decimal places.
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Hello,
I am making an app that displays products. Once you select a product, it shows you links to purchase it, as well as 3 review videos from YouTube. So far I have used the YouTube API to display video information, including video ID, title, etc. But I am unsure as to how to display the videos themselves. Below is my JavaScript file that displays the video information.
Could anyone tell me how to display videos based on the product name?
Thank you!
function showResponse(response) {
var responseString = JSON.stringify(response, '', 2);
document.getElementById('response').innerHTML += responseString;
}
function onClientLoad() {
gapi.client.load('youtube', 'v3', onYouTubeApiLoad);
}
function onYouTubeApiLoad() {
gapi.client.setApiKey('API_KEY');
search();
}
function search() {
var request = gapi.client.youtube.search.list({
part: 'snippet',
q: "paper towel review",
maxResults: 2,
order: "viewCount"
});
request.execute(onSearchResponse);
}
function onSearchResponse(response) {
showResponse(response);
}
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Dear all,
it's my simple JS program.
I can't figure out that why can't i stop the loop by using "guess==null".
Please help!!
var target = prompt("Please enter a number small than 50:");
var guess = "";
var time = 0;
do{
guess = prompt("Please Guess:");
if(guess == target || guess == null){
break;
}
if(guess < target){
alert("bigger!");
time++;
continue;
}else{
alert("smaller!");
time++;
continue;
}
}while(true)
if(guess==null){
document.write("the answer is:"+target);
}else{
document.write("Good!共猜了:"+(time+1));
}
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Try using the isNaN[^] function - i.e.:
isNaN(guess)
rather than
guess == null
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 really useful! thanks a lot!
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guess can return an empty string when you click on Ok without entering anything, guess will only be null if you click on cancel or if you close the prompt.
Add guess == '' to your if statement or replace guess == null with isNaN(guess) that will check if the value is a legal number
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 really useful! thanks a lot!
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A few things that might be helpful.
You don't really need to test for the 'break' options (as your code appears) if you
do something like this:
do {
if(something is true) {
do-this;
}
else
if(something else is true) {
do this;
}
. . . etc . . .
else break;
} while(true)
This style will handle anything 'unexpected' - that is, anything you didn't intend
| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein |
| "As far as we know, our computer has never had an undetected error." - Weisert |
| "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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really useful! thanks a lot!
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