Javascript Tutorials

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JavaScript object how to use Foreach loop

JavaScript's Array#forEach() function lets you iterate over an array, but not over an object. You can iterate over a JavaScript object using forEach() using Object.keys(), Object.values(), or Object.entries().

MapboxGL is not defined error solution

Fix mapboxgl is not defined. it's an easy fix you just have to include mepboxgl script into your Head section.

Mapbox production error in console Uncaught Reference Error

Fix Mapbox production error in console. "Uncaught ReferenceError: y is not defined". with Mapbox 2.0 version React app in the production environment gets this error and it's really easy to fix it.

Essential javascript array functions

Much more efficient and flexible Essential javascript array functions to use in daily routine. Great Power at no performance cost.

Javascript Questions

Lib to protect SQL/javascript injection for java/jsp

Anyone know a good lib where i can run the strings before they are inserted, that can strip out sql/javascript code? to be run in jsp pages.

How to split a string into an array in jQuery when there is only one element in the string?

I have this code, that takes a string and splits it into an array: nodes = $("#" + model_id + "-" + node_class + "--" +

How to efficiently count the number of keys/properties of an object in JavaScript

What's the fastest way to count the number of keys/properties of an object? is it possible to do this without iterating over the object? i.e.,

How can I find the keys of an object?

I know in javascript, objects double as hashes, but i have been unable to find a built-in function to get the keys: var h

Rotate SVG symbol to match aircraft heading using Google Maps API

I've been trying to rotate the google maps api svg aircraft symbol so it shows the aircraft's correct heading each time the symbol moves. it

Airport simulation in JavaScript with a fixed number of aircraft waiting to takeoff and land

I am working on a simplified airport simulator in javascript with very simple css or jquery animation to demonstrate a takeoff or a landing (such

Stop music from in flash from javascript event

I am attempting to stop the music inside of my flash swf that i have loaded in the page <object id="flashcontrol1"

Pop-out music player from a frame

I am currently coding a website for a band and i have a music player located within a frame in the website. i would like to make the music player

How can I remove Child2 by parent using js

I was going to remove child2 by parent, but its doesn't work var y = document.getelementbyid('parent');

Cannot navigate to child routes using router.navigate method or routerlink :: Error : Cannot match any routes. URL Segment: 'child2'

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data.json() is not a function (React)

I have the following code: getweather = e => { e.preventdefault(); const api_call = fetch(

DataTables how to call data.json properly

My data for a datatable is currently located at the bottom of my app.js and looks something like this: var data = {

I want to call the object in the data.json file

I want to call the object in the data.json file as an

Importing external "data.json" file into javascript variable

This may be a duplicate, but i was unable to find a previously asked question that answers mine. i am wanting to import a .json file into

I want to write an Async JSON contacts which will overwrite the content of my data.json file

I have written the file contact.js using

Pull random data from data.json and shuffle it

I have a json data sheet with a bunch of objects which i am displaying on my page { "objects": [ ... ] }

update d3 pie chart with new data.json

I have a dynamic data source that creates a new json in the browser frequently. i was able to create a pie chart from this json using the

How to call a function in views.py on clicking a button in template.html in django

I have a form in which there is a button . i want to call a view function named def recognize(): in my views.py but after clicking

call function in controller from template.html

I am new to angularjs, somehow while going through many sites now i am able to create a directive for showing some data.now i need to send some

jQuery .load template.html in pure Javascript

I am currently loading a template like this: $('#mydiv').load("template1.html") i'm currently using jquery, but

Getting Django Python data from views.py to javascript object in template.html

I'm using django's render_to_response to write data out to an html page, but i'd also like that render_ to _response call to load a

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How can I upload files without using an HTML <form>?

In a web application i am building i need to upload photos without using a form, otherwise it will come up with form embedded in an outer from

How do I Validate the File Type of a File Upload?

I am using <input type="file" id="fileupload" runat="server"> to upload a file in an asp.net application. i would like to limit

How to determine if user selected a file for file upload?

If i have a <input id="uploadfile" type="file" /> tag, and a submit button, how do i determine, in ie6

Vista Sidebar Gadget not showing flyout - System.Gadget.Flyout.show not setting true

I have a very strange bug going on. i cannot get the flyout to show on my gadget, despite having reproduced the flyout code character for

I've got a problem with a toggling sidebar using jQuery

I'm trying to create a simple toggling sidebar using jquery, where it expands and contracts when a button is pressed. the button also changes to

Firefox sidebar extension link loaded into a new browser tab. How-To?

I have a friefox sidebar extension. if its opened by clicking on the toolbar icon i load it with a webpage ( that i have authored ). now, if the

Is reduce an alternative to using map when I want to transform one array into another with _.lodash?

Given the object that we have created: var t2 = [ {"topicid":1,"subtopicid":1,"topicname":"a","subtopicname":"11"},

How do I specify [isSorted = true] when using the .uniq function in lodash?

I have the following array: var tst = [ {"topicid":1,"subtopicid":1,"topicname":"a","subtopicname":"11"},

Loop through properties in JavaScript object with Lodash

Is it possible to loop through the properties in a javascript object? for instance, i have a javascript object defined as this:

How can I remove an element from a list, with lodash?

I have an object that looks like this: var obj = { "objectivedetailid": 285, "objectiveid": 29, "number": 1,

Create chain in lodash with custom functions

Is there way to get my own custom function in a chain of lodash. so for example like this: var l = [1,2,3] var add = function(a,

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Lodash: Constructing single object from many - Merging/overriding properties

note: i filed this question under lodash as i'm pretty sure it can help me solve that problem nicely, but haven't put my finger on

Can I pass parameters to a function debounced with _.lodash?

I have been trying to use _lodash.debounce() and i have it working. however i am not sure if it's working the best way it could be. i looked at

In lodash, what is the opposite of `pairs()`?

I cant't see it in the docs - http://lodash.com/docs - please help me: what is the

How can I use lodash max against a jQuery array?

I'm trying to get the max rows out of two tables. what am i doing wrong? maxrows ends up being a tbody jquery element and not the max property

Lodash - difference between .extend() / .assign() and .merge()

In the lodash library, can someone provide a better explanation of

Javascript templates (eg.Underscore / Lodash): informative advice

I'm currently learning about javascript templates and i have an informative question. what is the benefit of populating a javascript

Sort items in an array by more than one field with lodash

How can i sort an array of objects by more then one field using lodash. so for an array like this: [ {a: 'a', b: 2}, {a: 'a',

How to reshape an array with lodash

I wonder what is the idiom which used in lodash for reshaping arrays? basically, i'm looking for something that transforms this array :

Using lodash array functions on Restangular collections

I'm using restangular with angularjs, and i would like to iterate over a collection in a function of the controller, where i need to modify a

How to break an array of objects into 2 arrays, using Underscore/LoDash

I have an array of objects: var arr = [ {field1: value, field2: value, field3: value, field4: value}, {field1: value, field2:

Lodash: how do I use filter when I have nested Object?

Consider this example. i am using lodash 'data': [ {

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unique union in lodash

I have two kind of collections: fieldmappingviewmodel.mappedfields(): [ { "emailfield" : "firstname", "crmfield" :

Using lodash/underscore in nested each

I'm trying to convert this block of code to lo-dash: if(!event && callback){ for(var ev in this._events){ for (var i

Is it possible to add non html comment in underscore.js or lodash templates?

Is it possible to add non html comments in underscore.js or lodash ? something like : <%-- we do this here because...

lodash bind function using as jQuery eventHandler... is it possible?

I'm new to lo-dash, and wanted to know is it possible to use _.bind as $.bind and how can i accomplish this? i really

Differences between Lodash and Underscore.js

Why would someone prefer either the lodash or

Set lodash / underscore template settings globally using require.js

Is there a way to set the templatesettings for lodash when using

Split JavaScript array in chunks using Lodash

I need to split a javascript array into n sized chunks. e.g.: given this array ["a1", "a2", "a3", "a4", "a5",

Looking for doc on why IE "yellow bar" shows when opening a HTML file that contains JavaScript

I have a site, from which you can download an html file. this html file contains a form with hidden fields, which is right away posted back to the

Hiding toolbar / status bar with javascript in CURRENT browser window?

Is there some way to hide the browser toolbar / statusbar etc in current window via javascript? i know i can do it in a popup with

How to implement file upload progress bar on web?

I would like display something more meaningful that animated gif while users upload file to my web application. what possibilities do i have?

Make browser window blink in task Bar

How do i make a user's browser blink/flash/highlight in the task bar using javascript? for example, if i make an ajax request every 10 seconds to

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Where do I put "main.js" file in Gatsby project?

I have a function that grabs an element and adds the class "is-open" in order to toggle an accordion. i have put this function in my

how to dispatch a action to save data in store in next js

What i want to do is dispatch an action in my set interval function and not in get initial props and save my data in store and how to get that

React hook useState with array cause missing render calls

I have following code: function mycomponent( props ) { let arrsize = 5; const [arr, setarr] = usestate( () => {

React JS - onChange function is being triggered twice

I got an issue while working with date input in react. so the date value is coming from graphql and format of date is

React hooks using recharts AreaChart Console Warning

I implemented areachart from recharts on my app like this: import react from 'react'; import { areachart, area, xaxis,

trying to execute a function that is passed to a component using context

I am trying to learn the concept of context in react, i am trying to

How to use reselect createStructuredSelector function with typescript?

I am trying to build an react redux typescript app. i am using reslect library to create selectors. i am getting an error while

Focus property not working with styles, but before focus style works

I'm trying to change the font color of textinput for material ui, but it's not working. it changes the font color when i click away, (it becomes

How to make canvas drawing always center

I'm working on the visualization of a box inside another box. i did the props for changing the height, width, length of the outer box and

Trouble understanding doc().get() in firebase

I am having a bit of trouble understanding why my code is not working. i am trying to read data from firebase inside a react-native project. i can

Why are my JavaScript Date/Time objects stored as maps as opposed to timestamps in Cloud Firestore?

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500 error response to CORS preflight OPTIONS when calling cloud function. How can I call a cloud function from my web-app and be CORS compliant?

I'm trying to incorporate cloud functions into my web-app. unfortunately i'm getting cors errors that i'm struggling to handle.

How to create template strings in typescript?

I am trying to create some string literals for my code in typescript on the firebase cloud functions platform. i am using vs code as my code

Delete fields from a firestore document using nodejs

I'm attempting to delete fields from a firestore document with no success. i've searched for the error messages that i get but the few

Using form instead of div

I have login page. in which i am using form. it never worked. later i tried div and it works fine. can anyone tell me why it does not work with

Generating Search suggestions in React?

I am looking to generate search suggestions that match data collected, like so:

CSS Media Queries not sufficient enough to detect extra large mobile/tablet devices vs desktop

Usually, when detecting mobile or tablet devices against a desktop, i use the following media queries. @media only screen and

ReactJS: Duplicates arising while creating mouse over event

I am trying to create cards in my react project.my current project the

useState object set

I am new to reactjs and working with hooks. i want to set state for object. here is my code: const startpage = (props)=> {

React JS Cards using For loop

I can't manage to dynamically produce more than one 'card' in my react webpage. i import the data from database.js, but i'm clearly not

Curried function causing error but works if not curried

Export const postmoviepopular = url = dispatch => { const data = axios.get(url); dispatch(savemoviepopular(data)); } const

How to add an icon to the options in react-select?

Attempts to add an icon to option in react-select. i imported svg icons from the files england.svg, germany.svg. i

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how to call react handler manually from another javascript file?

How to call react handler manually from another javascript file? import './external/myplugin' class title extends component {

passing text as prop in SVG file - React

I have a avatar.svg image which consists of following file content <?xml version="1.0" encoding="utf-8"?> <svg

Firebase authentification via GitHub: setting the uid

I want to allow users to sign in/up via github and via email/password using firebase. in the server side, i implemented using the

How to display store items in v-for loop with Vuetify grid?

I am attempting to display card items in a v-for loop with vuetify grid system. the loop is set up to iterate through dynamically inputted

inserting a videotag inside a dynamically created div

I am a beginer to javascript.i want to create a div dynamically,and then i want to set a video tag inside that div.after that write this div

How can I set the number of decimals on a popup using JavaScript?

I have a popup on a website that displays values from a geojson file. right now, it looks as in the picture below:

How to call a function present parallel to calling function in React context API

I have a function update() in webcontextprovider, from which i want to call another function updateagain()

Cannot import @material-ui/core/styles/MuiThemeProvider

I am working on a react project, using material ui react components. i want to import muithemeprovider in src/index.js

State values resetting after onSubmit even if not successful

I have a form, and if i do a submit and it returns an error, i programmed it to show me where the errors are. after fixing only the errors and i

How to use Hook API style

I am learning 'how to style material ui components'. in the tutorial it gives you this hook api code below: import react from

Why does my react-router link bring me to the middle of a page?

I've got many links on my site but only one that does this. instead of bringing me to the top with the navbar, it just goes to the middle

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How to edit multiple fields in single column material-table

I'm using material-table for a project. there i have a

How to set the state in Redux from a component passing payload?

I can't set the state with mapdispatchtoprops and pass the payload imports: import react, { component } from 'react';

jest just passed all test even it is false

I'm testing my vue.js app with jest. and i realized that jest just passed all those test even it should be fail. for example this one should be

Trying to display a video inside a modal in react native

I am trying to display a youtube video inside a modal in react native. video gets displayed in the normal view(i.e., without a modal

IOS Keyboard wont dismiss when using search bar in react site

I am probably taking the wrong approach but i am working on a react site that has a search bar. on ios/safari if the user taps into the search the

What is the difference between the different ways of importing material-ui components?

From reading the material-ui documentation and online examples, there seem to be different ways of importing the same item: import

Using comparison in useEffect's dependency array

I'm creating a search input with a submit button and a clear button. when submit button is clicked, it will trigger a search request with

How to solve a function call that uses useState with getting "Too many re-renders. React...."

Context: i'm using react hooks. what i'm doing is a onclick={sorttable(valuepassed)} and check a state value

Why is my Firestore document wrapped inside a MAP object?

Upon pushing my event to firestore, my data inside the event id's is wrapped inside another event(supposedly, map() object). why is this the case?

Problem in adding data through admin.firestore()

My current firestore rules in my project:

LinkError: WebAssembly.instantiate() function import requires a callable

I am practicing webassembly at

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Env-cmd environment variables in React

I seem to have tried every which way variation of the env-cmd command but cannot work out why i can't access the variables i originally

Material-UI Popover component does trigger onClose event

I am using material-ui popover component, the open of popover component is handled by its state, i defined a function named handlepopoverclose to

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