I'm trying to use some function defined in a file inside a HTML script tag.
Here is the javascript file myfunction.js:
fct = function() {
};
Inside index.html I have:
<script src="./myfunction.js"></script>
<script>
fct.some.property = function() {
}
</script>
It says fct.some is undefined on the console.
How to define some inside fct so that I can use it in oter scripts ? I don't want to use any librairies.
I tried the following but it does not work :
fct = function() {
return {
some: {}
}
};
I can't reproduce the error; when I test your code as-is I get
fct.some is undefined
The fix is:
fct.some = {};
fct.some.property = function() {
}
This works fine for me.
To make sure I have your question right, it looks like you are trying
to use a function that you wrote in a javascript file directly in
your html file, but you are having an issue with it coming back as
undefined.
In testing it I found that as long as the fct function in your .js is global then it will work, but there is another problem with your example in the HTML ( but it may just be a typo because it's an example)
You put the script src for the .js file in above the in-inline js correctly, but then in the inline js script tag you say:
fct.some.property = function(){}
The problem with this is .some is not defined yet, so you can't attach a property to it yet. Try:
fct.some = {} // empty object
fct.some.property = function(){}
EDIT: So, this works on repl.it, but it won't work in the stackoverflow snippet editor. In the snippet editor it gives me the same error as you are getting. Odd.
let fct = function() {
}
<!DOCTYPE html>
<html>
<head>
<link href="index.css" rel="stylesheet" type="text/css" />
</head>
<body>
<script src="index.js"></script>
<script>
console.log(fct)
fct.some = {}
fct.some.property = function() {
return 7
}
console.log(fct.some.property())
</script>
</body>
</html>
You are correctly importing the JS file. Just check it is in head tag of html. You are getting this issue because you want to assign "property" to "some" of fct. As you have not define here what is "some". I have tried to resolve your problem by deleting "some"
index.html
<html>
<head>
<script src="myfunction.js"></script>
</head>
<script>
fct.some = function() {
}
</script>
<body>
</body>
</html>
myFunction.js
fct = function() {
};
Here are some links which can be useful for you adding custom properties to a function
Related
I have 2 files the first one is an HTML file the other one is a javascript file. What I was trying to do was define a variable on the javascript file and access it on the Html side. Is it possible? A rough code is attached below but it doesn't work I get favColor is not defined error. thanks in advance.
JS Side
const favColor = "red"
Html side
<script src="pathtojsfile"></script>
<p id="insertHere"></p>
<script>
document.getElementById("insertHere").innerHTML = favColor
</script>
It is widely considered bad practice to work with global variables. To avoid it, you can make use of ECMAScript Modules, introduced back in 2015 with ES6/ES2015.
This allows your first Javascript, let's name it colors.module.js to export the variable:
export const favColor = 'red';
Then, in your script that needs to access this variable, you import it:
import { favColor } from '/path/to/js/modules/colors.module.js';
For that to work, you need your importing script to have type=module attribute, and the import must be done on top of your Javascript. The script you import from does not need to be included in the page.
Here's some helpful links to get you started with modules:
ES Modules Deep Dive
Javascript Modules on MDN
Flavio Copes' take on ES Modules
I've set up a tiny github repo demonstrating this very basic usage of an ES module.
If modules are not an option, e.g. because you must support IE 11, or your build stack doesn't support modules, here's an alternative pattern that works with a single namespace object you attach to the global object window:
// colors.module.js
window.projectNamespace = window.projectNamespace || {};
projectNamespace.colors = window.projectNamespace.colors || {};
projectNamespace.colors.favColor = 'red';
and in your page you access it from that name space:
document.getElementById("insertHere").innerHTML = window.projectNamespace.colors.favColor;
This way you have a single location to put all your globally accessible variables.
As the code is written in your example it should work fine. Just like my example here:
<script>
const favColor = "red";
</script>
<p id="insertHere"></p>
<script>
document.getElementById("insertHere").innerHTML = favColor;
</script>
But there can be a number of issues if the code is not like this. But the JavaScript code could just go in the same file. Try to separate the html from the JS like this (the code in the script element could be moved to it's own file):
<html>
<head>
<script>
const favColor = "red";
document.addEventListener('DOMContentLoaded', e => {
document.getElementById("insertHere").innerHTML = favColor;
});
</script>
</head>
<body>
<p id="insertHere"></p>
</body>
</html>
Here I'm also adding the eventlistener for DOMContentLoaded, so that I'm sure that the document is loded into the DOM.
Where your variable is declared is not the problem per se, but rather the loading order of scripts.
If you want to make sure external scripts are loaded before you execute yours, you can use the load event of window object. It will wait until all resources on your page are loaded though (images, css, etc.)...
const myvar = "Hey I'm loaded";
<!DOCTYPE html>
<html lang="en">
<head>
<title>Document</title>
<script>
//console.log(myvar); //<- fails
window.addEventListener('load', e => {
document.querySelector('#insertHere').innerHTML = myvar;
});
</script>
</head>
<body>
<p id="insertHere"></p>
</body>
</html>
Or you can put all your code in js files, and they will be invoked in the order they are declared.
Edit
Given objections and more questions popping in the comments, I'll add this. The best and cleanest way to achieve this remains to put your code in a .js file of its own and put all your <script> tags inside <head>, with yours last, as it relies on others to run.
Then you can either add the attribute defer to your <script> or have everything wrapped in an event handler for DOMContentLoaded so that it gets run after the DOM is fully loaded.
<!DOCTYPE html>
<html lang="en">
<head>
<title>Document</title>
<script src='other1.js'></script> <!-- let's say this one declares myvar -->
<script src='other2.js'></script>
<script src='other3.js'></script>
<script src='myscript.js'></script>
</head>
<body>
<p id="insertHere"></p>
</body>
</html>
myscript.js
window.addEventListener('DOMContentLoaded', e => {
document.querySelector('#insertHere').innerHTML = myvar;
});
Is it possible to call a function declared in a .js file from the body of the HTML. I'm assuming the reason it won't work is because the .js file is called after the function has been called in the HTML body. Is there a way around this.
I've had a look at some answers here, but can't seem to find what I'm looking for. My apologies if it's staring at me as a beginner I may not be using the correct terminology.
jqueryfunctions.js:
function someFunction() {
// do.something;
}
index.html:
<html>
<head>
<script type="text/javascript" src="//code.jquery.com/jquery-1.8.3.js"></script>
<script src="jqueryfunctions.js"></script>
</head>
<body>
<script>
someFunction();
</script>
</body>
</html>
Here is the full/actual .js file returnedMessage() is the function I was reffering to as someFunction().
The console error I'm getting is "returnedMessage() is not defined".
$(function(){
var timer = null;
function appendmessageBox() {
$('body').append('<div id="messageBox" class="datamessagebox"> </div> ');
}
// just before body tag.
appendmessageBox();
// makes MessageBox Disappear on MouseOver
$('#messageBox').on('mouseover click', function(){
$(this).fadeOut(300);
});
function returnedMessage(message) {
if (timer) {
clearTimeout(timer); //cancel the previous timer.
timer = null;
}
$( '#messageBox' ).css('display', 'inline-block');
timer = setTimeout(function(){
$( '#messageBox' ).fadeOut( 499 );
}, 5000);
$( '#messageBox' ).append('<msg>'+message+'<br /></msg>').fadeIn( 200 );
$( '#messageBox > msg:last-of-type' ).delay(3000).fadeOut( 3000 );
setTimeout(function(){
$( '#messageBox > msg:first-of-type' ).remove();
}, 5999);
}
// This test message bellow works correctly.
returnedMessage('hello world - test 1');
});
EDIT:
you should define your function like so:
var someFunction = function() {
// do something
}
Or like so
function someFunction() {
// do something
}
But always use the function word. More information on function definition in Javascript.
More about JS file import
Javascript code is inserted between <script> tags in an HTML file
<script>
console.log("Hello World!");
</script>
You usually place those script tags inside the <head> tag. However it's recommended you put them after your <body>. This way you allow the DOM to load before you run your JS script. This is important for exemple when you want to select elements in the DOM. If you put the JS code before the actual HTML that creates this element, then JS will not find the element you would be looking for because it doesn't yet exist.
Now it's not really efficient to work with script in your HTML code so it's helpful to write JS in .js files and then import them in you HTML file like you would for a CSS file. Use the <script> to do so:
<script src="myScript.js"></script>
You can use multiple <script> tags to pull in multiple JS files. But you need to be careful of the order you write them. For instance you have a functions.js file that holds all your functions, and a menu.js that handles the menu on your application. You're using functions from the code functions.js in menu.js so you need to import the files in this order:
<script src="functions.js"></script>
<script src="menu.js"></script>
First declared, first loaded.
You can write own function like this:
Here you can see simple example: https://jsbin.com/munowupipo/edit?html,output
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Define a Function in jQuery</title>
<script src="https://code.jquery.com/jquery-2.1.0.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$.fn.myFunction = function() {
alert('You have successfully defined the function!');
}
$(".call-btn").click(function(){
$.fn.myFunction();
});
});
</script>
</head>
<body>
<button type="button" class="call-btn">Click Me</button>
</body>
</html>
Maybe you want to take the function on document is ready, so you must to write:
<script>
$(document).on("ready", function() { yourfunction(); });
</script>
I'm making a game in JS using P5, and I came upon a problem.
In my html file I have references to .js files:
<!DOCTYPE html>
<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.3/p5.min.js"></script>
<script src="main.js"></script>
<script src="isKeyPressed.js"></script>
<script src="blocks.js"></script>
<script src="player.js"></script>
</head>
<body>
</body>
</html>
I have one .js file defining the function isKeyPressed():
function isKeyPressed(keyQuery) {
var did = false;
for(var i = 0; i < keysPressed; i++) {
if(keysPressed[i] === keyQuery) {
did = true;
}
}
return did;
}
I reference this in another object inside player.js:
player.motion = function() {
if(isKeyPressed('w')) {
this.velocity.add(0,-5);
}
if(isKeyPressed('s')) {
this.velocity.add(0,5);
}
if(isKeyPressed('a')) {
this.velocity.add(-5,0);
}
if(isKeyPressed('d')) {
this.velocity.add(5,0);
}
}
But when I try to call player.motion, I get the error:
Uncaught TypeError: isKeyPressed is not a function
Does anyone know why this is occurring?
For the record, I don't think the accepted answer is correct. Specifically, I don't think the accepted answer really changes anything from what you were originally doing. My guess is that you had another problem in your code (like a syntax error) that was causing this error, and you fixed that in the process of implementing the suggested solution. So while it might look like the solution fixed your problem, really it was something else.
I'm providing this alternative answer so you don't think you have to define your JavaScript in your html directly, as that is definitely not the case.
I tried testing out your setup by creating a smaller example consisting of three files:
index.html
<!DOCTYPE html>
<html>
<head>
<script src="one.js"></script>
<script src="two.js"></script>
</head>
<body onload="printObj()">
</body>
</html>
one.js
function printOne(){
console.log("one");
}
two.js
var obj = {};
obj.printTwo = function(){
console.log("two");
printOne();
}
function printObj(){
obj.printTwo();
}
This is pretty much exactly what your setup is, and it works fine. You absolutely do not need to put your JavaScript in your html. As long as the JavaScript files are correctly loaded in the proper order, then you can use functions and variables from one file in another file.
There are two main things that could cause your problem:
Are your files correctly loaded?
Are there any syntax errors you haven't noticed? (This is my guess as to what caused your original problem.) Check the JavaScript console, and try running some test code to actually run the functions you're trying to call.
Did you get all the file names correct?
Are you behind a firewall, or are there other network problems that might cause a problem with loading?
Are your files loaded in the proper order?
For file two.js to access code defined in one.js, you have to make sure one.js is loaded before two.js. It looks like you've done this correctly, but are you sure the JavaScript is where you think it is?
In other words, are you sure it was in player.js and not in main.js?
You might want to get rid of this ambiguity by placing related JavaScript in the same file. It doesn't make a ton of sense to have one file define a keysPressed array and then another file use that array to define an isKeyPressed() function. Just put them in the same file, and make sure that file is loaded before other files that use it.
The accepted answer doesn't change anything with regard to when stuff is loaded. Unless you had a syntax error, or the player.motion() function was actually in the main.js file, or you had a network loading problem, your code should have worked. So one of those things must be your actual problem. You do not have to define your JavaScript in your html for it to work.
I recommend not making a file name have capitals. So change it from
<script src="isKeyPressed.js"></script>
to
<script src="iskeypressed.js"></script>
also change the file name too.
You could try something like this
<!DOCTYPE html>
<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.5.3/p5.min.js"></script>
<script src="main.js"></script>
<script src="isKeyPressed.js"></script>
<script src="blocks.js"></script>
<script src="player.js"></script>
<script>
player.motion = function() {
if(isKeyPressed('w')) {
this.velocity.add(0,-5);
}
if(isKeyPressed('s')) {
this.velocity.add(0,5);
}
if(isKeyPressed('a')) {
this.velocity.add(-5,0);
}
if(isKeyPressed('d')) {
this.velocity.add(5,0);
}
}
</script>
</head>
<body>
</body>
</html>
This is importing all functions from the isKeyPressed.js file and therefore you are able to reference it in the <script> tag. You were not able to use isKeyPressed.js's functions in player.js because you cannot reference it.
I'm writing java script code in script tag in head like:
<head>
<script language="javascript">
object o = new object({....});
</script>
</head>
and trying to use object a in body tag
<body>
<script>
alert(o.value);
</script>
</body>
how can i access object from body???
is their any alternatives?
<head>
<script language="javascript">
var o = new Object();
o.value="a"
</script>
</head>
<body>
<script>
$(document).ready(function()
{
alert(o.value)
});
</script>
</body>
In this case var a is accessible in complete application, but one thing you need to make sure if you are using external JS files then it must be loaded when you using the variable. try onload function to assure JS is loaded and ready to use in body:
window.onload = function ()
{
alert(a);
}
Since your variable is declared outside any functions it can be accessed from anywhere in your document from the same script block or from a seperate script block like in your example. it can even be accessed from html event-attributes like this (note that its better to attach events to html elements using using js):
<button onclick="alert(a);">Click this button to open an alert!</button>
I have a probably very simple problem that is completely spoofing me.
I have got a web server (XAMPP) running off a reasonably slow usb stick.
I've got a very simple file structure:
--htdocs
--projects
--callback
index.html
--js
jquery-1.9.1.min.js
callbackclient.js
--css
main.css
For some reason, I can't get a simple linked script working:
Here is my index.html
<!DOCTYPE HTML>
<html>
<head>
<script src='js/jquery-1.9.1.min.js' type='text/javascript'></script>
<script src='js/callbackclient.js' type='text/javacsript'></script>
<link href='css/main.css' rel='stylesheet' type='text/css'>
</head>
<body>
This is a test
</body>
<script>
$(document).ready(function(){
tester();
});
</script>
</html>
And here's my callbackclient.js:
function tester(){ console.log("test");
}
When I hit localhost/projects/callback the browser displays "This is a test" as expected, but I get an error in the console:
Uncaught ReferenceError: tester is not defined
I get the same if I try to run tester(); from console directly, yet $("head") correctly selects the head element which I guess means jQuery is being loaded fine.
I must have missed something fundamental - someone please enlighten me!
It could be that you misspelled the type on the script tag. text/javacsript instead of text/javascript
Try this inside your callbackClient.js:
var tester = function (){ console.log("test"); }
If that works, you just need to have the function be set to a variable, and then call it. If that doesn't work, then I would just remove the JS code on your HTML page and do this inside your callbackClient.js:
jQuery(function () {
// Logic here
console.log('this is working, right?');
var functionName = function () {
console.log('blah blah blah')
}
functionName();
})
Hope that helps!