What is the ‘new’ keyword in JavaScript?

The new keyword in JavaScript can be quite confusing when it is first encountered, as people tend to think that JavaScript is not an object-oriented programming language. What is it? What problems does it solve? When is it appropriate and when not? Answer It does 5 things: It creates a new object. The type of this object is simply object. It sets this new object’s internal, inaccessible, [[prototype]] (i.e. __proto__) property to be the constructor function’s external, accessible, prototype object (every function object automatically has a prototype property). It makes the this variable point to the newly created object. It

jQuery – setting the selected value of a select control via its text description

I have a select control, and in a javascript variable I have a text string. Using jQuery I want to set the selected element of the select control to be the item with the text description I have (as opposed to the value, which I don’t have). I know setting it by value is pretty trivial. e.g. But I’m a bit stumped on doing it via the text description. I guess there must be a way of getting the value out from the text description, but my brain is too Friday afternoon-ed to be able to work it out. Answer

How do you remove all the options of a select box and then add one option and select it with jQuery?

Using core jQuery, how do you remove all the options of a select box, then add one option and select it? My select box is the following. EDIT: The following code was helpful with chaining. However, (in Internet Explorer) .val(‘whatever’) did not select the option that was added. (I did use the same ‘value’ in both .append and .val.) EDIT: Trying to get it to mimic this code, I use the following code whenever the page/form is reset. This select box is populated by a set of radio buttons. .focus() was closer, but the option did not appear selected like it

push multiple elements to array

I’m trying to push multiple elements as one array, but getting error I’m trying to do similar stuff that I’d do in ruby, I was thinking that apply is something like *. Answer When using most functions of objects with apply or call, the context parameter MUST be the object you are working on. In this case, you need a.push.apply(a, [1,2]) (or more correctly Array.prototype.push.apply(a, [1,2]))

Javascript disabling Div element on submit

The code below just hides the movie that I am playing behind. Remove element (if possible) or disable it, specially movie playing in background. I tried using document.video.disabled=true; but its not working. Any idea how to go around this problem please? Answer Try

Logic for multiple and single select/combo boxes

Below is my code: When select-box or combo-box is looped for ten times then I am getting form[“city”] length as 10 properly and behaviour of alerts within combox-box is appropriate, but if I have a single-select-box, then instead of giving form[“city”] length as 1 it gives it as 4 which is the number of option elements in my dropdown-box. So my logic doesn’t work here. How do I make it work for both single as well as multiple combo/select boxes. Any help would be appreciated. Answer Please use a javascript library like jQuery for cross-browser compatibility. You can use the

Getting current date and time in JavaScript

I have a script that prints the current date and time in JavaScript, but the DATE is always wrong. Here is the code: It should print 18/04/2012 15:07:33 and prints 3/3/2012 15:07:33 Answer .getMonth() returns a zero-based number so to get the correct month you need to add 1, so calling .getMonth() in may will return 4 and not 5. So in your code we can use currentdate.getMonth()+1 to output the correct value. In addition: .getDate() returns the day of the month <- this is the one you want .getDay() is a separate method of the Date object which will

How to read data From *.CSV file using javascript?

My csv data looks like this: heading1,heading2,heading3,heading4,heading5,value1_1,value2_1,value3_1,value4_1,value5_1,value1_2,value2_2,value3_2,value4_2,value5_2…. How do you read this data and convert to an array like this using Javascript?: [heading1:value1_1 , heading2:value2_1, heading3 : value3_1, heading4 : value4_1, heading5 : value5_1 ],[heading1:value1_2 , heading2:value2_2, heading3 : value3_2, heading4 : value4_2, heading5 : value5_2 ]…. I’ve tried this code but no luck!: Answer NOTE: I concocted this solution before I was reminded about all the “special cases” that can occur in a valid CSV file, like escaped quotes. I’m leaving my answer for those who want something quick and dirty, but I recommend Evan’s answer for accuracy. This

Connecting NodeJS app to SignalR (with .NET Core 3)

I have a server running SignalR using .NET Core 3. The project was started with the template and I followed a guide (https://docs.microsoft.com/en-gb/aspnet/core/tutorials/signalr?tabs=visual-studio&view=aspnetcore-3.0). I have created a clone of the project, and can successfully connect to the server and can receive messages as expected. This also means I added CORS. I want to be able to use SignalR in a Node JS environment, but the connection stucks at “Negotiation” I have created a brand new folder, ran npm init -y and npm i @microsoft/signalr. Created a new js file called main.js, which looks like this: after running it with node

How to show No Data Available Message in highcharts

Can we show a message using highcharts.When the data is not available? we have to show a message Example : No Data Available. If we have data hide : No Data Available message . in highcharts dynamically Answer You can use Highcharts Chart Renderer Here’s an example in JSFiddle