I wanted to call a function defined in a first.js file in second.js file. Both files are defined in an HTML file like:
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
I want to call fn1() defined in first.js in second.js. From my searches answers were if first.js is defined first it is possible, but from my tests I haven't found any way to do that.
Here is my code:
second.js
document.getElementById("btn").onclick = function() {
fn1();
}
first.js
function fn1() {
alert("external fn clicked");
}
A function cannot be called unless it was defined in the same file or one loaded before the attempt to call it.
A function cannot be called unless it is in the same or greater scope then the one trying to call it.
You declare function fn1 in first.js, and then in second you can just have fn1();
1.js:
function fn1 () {
alert();
}
2.js:
fn1();
index.html :
<script type="text/javascript" src="1.js"></script>
<script type="text/javascript" src="2.js"></script>
You could consider using the es6 import export syntax. In file 1;
export function f1() {...}
And then in file 2;
import { f1 } from "./file1.js";
f1();
Please note that this only works if you're using <script src="./file2.js" type="module">
You will not need two script tags if you do it this way. You simply need the main script, and you can import all your other stuff there.
1st JS:
function fn(){
alert("Hello! Uncle Namaste...Chalo Kaaam ki Baat p Aate h...");
}
2nd JS:
$.getscript("url or name of 1st Js File",function(){
fn();
});
You can make the function a global variable in first.js
and have a look at closure and do not put it in document.ready put it outside
you can use ajax too
$.ajax({
url: "url to script",
dataType: "script",
success: success
});
same way you can use jquery getScript
$.getScript( "ajax/test.js" )
.done(function( script, textStatus ) {
console.log( textStatus );
})
.fail(function( jqxhr, settings, exception ) {
$( "div.log" ).text( "Triggered ajaxError handler." );
});
declare function in global scope with window
first.js
window.fn1 = function fn1() {
alert("external fn clicked");
}
second.js
document.getElementById("btn").onclick = function() {
fn1();
}
include like this
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
use "var" while creating a function, then you can access that from another file. make sure both files are well connected to your project and can access each other.
file_1.js
var firstLetterUppercase = function(str) {
str = str.toLowerCase().replace(/\b[a-z]/g, function(letter) {
return letter.toUpperCase();
});
return str;
}
accessing this function/variable from file_2.js file
firstLetterUppercase("gobinda");
output => Gobinda
It should work like this:
1.js
function fn1() {
document.getElementById("result").innerHTML += "fn1 gets called";
}
2.js
function clickedTheButton() {
fn1();
}
index.html
<html>
<head>
</head>
<body>
<button onclick="clickedTheButton()">Click me</button>
<script type="text/javascript" src="1.js"></script>
<script type="text/javascript" src="2.js"></script>
</body>
</html>
output
Try this CodePen snippet: link .
Please note this only works if the
<script>
tags are in the body and NOT in the head.
So
<head>
...
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
</head>
=> unknown function fn1()
Fails and
<body>
...
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
</body>
works.
This is actually coming very late, but I thought I should share,
in index.html
<script type="text/javascript" src="1.js"></script>
<script type="text/javascript" src="2.js"></script>
in 1.js
fn1 = function() {
alert("external fn clicked");
}
in 2.js
fn1()
Use cache if your server allows it to improve speed.
var extern =(url)=> { // load extern javascript
let scr = $.extend({}, {
dataType: 'script',
cache: true,
url: url
});
return $.ajax(scr);
}
function ext(file, func) {
extern(file).done(func); // calls a function from an extern javascript file
}
And then use it like this:
ext('somefile.js',()=>
myFunc(args)
);
Optionally, make a prototype of it to have it more flexible. So that you don't have to define the file every time, if you call a function or if you want to fetch code from multiple files.
first.js
function first() { alert("first"); }
Second.js
var imported = document.createElement("script");
imported.src = "other js/first.js"; //saved in "other js" folder
document.getElementsByTagName("head")[0].appendChild(imported);
function second() { alert("Second");}
index.html
<HTML>
<HEAD>
<SCRIPT SRC="second.js"></SCRIPT>
</HEAD>
<BODY>
method in second js<br/>
method in firstjs ("included" by the first)
</BODY>
</HTML>
window.onload = function(){
document.getElementById("btn").onclick = function(){
fn1();
}
// this should work, It calls when all js files loaded, No matter what position you have written
});
// module.js
export function hello() {
return "Hello";
}
// main.js
import {hello} from 'module'; // or './module'
let val = hello(); // val is "Hello";
reference from https://hype.codes/how-include-js-file-another-js-file
My idea is let two JavaScript call function through DOM.
The way to do it is simple ...
We just need to define hidden js_ipc html tag.
After the callee register click from the hidden js_ipc tag, then
The caller can dispatch the click event to trigger callee.
And the argument is save in the event that you want to pass.
When we need to use above way ?
Sometime, the two javascript code is very complicated to integrate and so many async code there. And different code use different framework but you still need to have a simple way to integrate them together.
So, in that case, it is not easy to do it.
In my project's implementation, I meet this case and it is very complicated to integrate. And finally I found out that we can let two javascript call each other through DOM.
I demonstrate this way in this git code. you can get it through this way. (Or read it from https://github.com/milochen0418/javascript-ipc-demo)
git clone https://github.com/milochen0418/javascript-ipc-demo
cd javascript-ipc-demo
git checkout 5f75d44530b4145ca2b06105c6aac28b764f066e
Anywhere, Here, I try to explain by the following simple case. I hope that this way can help you to integrate two different javascript code easier than before there is no any JavaScript library to support communication between two javascript file that made by different team.
<html>
<head>
<link rel="stylesheet" type="text/css" href="css/style.css" />
</head>
<body>
<div id="js_ipc" style="display:none;"></div>
<div id="test_btn" class="btn">
<a><p>click to test</p></a>
</div>
</body>
<script src="js/callee.js"></script>
<script src="js/caller.js"></script>
</html>
And the code
css/style.css
.btn {
background-color:grey;
cursor:pointer;
display:inline-block;
}
js/caller.js
function caller_add_of_ipc(num1, num2) {
var e = new Event("click");
e.arguments = arguments;
document.getElementById("js_ipc").dispatchEvent(e);
}
document.getElementById("test_btn").addEventListener('click', function(e) {
console.log("click to invoke caller of IPC");
caller_add_of_ipc(33, 22);
});
js/callee.js
document.getElementById("js_ipc").addEventListener('click', (e)=>{
callee_add_of_ipc(e.arguments);
});
function callee_add_of_ipc(arguments) {
let num1 = arguments[0];
let num2 = arguments[1];
console.log("This is callee of IPC -- inner-communication process");
console.log( "num1 + num2 = " + (num1 + num2));
}
better late than never
(function (window) {const helper = { fetchApi: function () { return "oke"}
if (typeof define === 'function' && define.amd) {
define(function () { return helper; });
}
else if (typeof module === 'object' && module.exports) {
module.exports = helper;
}
else {
window.helper = helper;
}
}(window))
index html
<script src="helper.js"></script>
<script src="test.js"></script>
in test.js file
helper.fetchApi()
I have had same problem. I have had defined functions inside jquery document ready function.
$(document).ready(function() {
function xyz()
{
//some code
}
});
And this function xyz() I have called in another file. This doesn't working :) You have to defined function above document ready.
TLDR: Load Global Function Files first, Then Load Event Handlers
Whenever you are accessing an element within a JS file or <script> block, it is essential to check to make sure that element exists, i.e., jQuery's $(document).ready() or plain JS's document.addEventListener('DOMContentLoaded', function(event)....
However, the accepted solution does NOT work in the event that you add an event listener for the DOMContentLoaded, which you can easily observe from the comments.
Procedure for Loading Global Function Files First
The solution is as follows:
Separate the logic of your JS script files so that each file only contains event listeners or global, independent functions.
Load the JS script files with the global, independent functions first.
Load the JS script files with event listeners second. Unlike the other previous files, make sure to wrap your code in document.addEventListener('DOMContentLoaded', function(event) {...}). or document.Ready().
<html>
<head>
<script>
function test(){
return function(){
alert("hi");
}
}
test();
</script>
</head>
<body>
</body>
</html>
This is my code, can I ask why it doesnt work properly??
Because you're returning your function but not invoking it.
Try this:
test()();
Here is a fiddle
I think you might be confused. test() returns a function reference, but it won't execute it.
You could do something like this
var alertFunc = test(); // return function reference
alertFunc(); // call the function
I've searched, but I could not find the solution to this problem. For some reason function doesn't get called when page loads the first time, only after refreshing the page it gets called. Examples:
function init() {
alert("hello");
}
Either calling the function with following method:
$(window).load(function () {
init();
});
Or inside a body tag:
<body onLoad="init()">
Also, this problem doesn't occur when I open page directly, only when I'm being linked to the page from another page.
Solved, mobile options must be set before loading jquery.mobile.
<script language=javascript>
$(document).bind("mobileinit", function () {
$.mobile.ajaxLinksEnabled = false;
$.mobile.ajaxEnabled = false;
});
</script>
<script src="scripts/jquery.mobile-1.2.0.js"></script>
Try something in the lines of:
function init() {
alert('Hello!');
}
window.onload(function() {
init();
}
I think the pop window with OK string will be dislayed afetr 5s after I click the button, but the pop window dispalyed immediately after I click the button, why?
Thanks!
<html>
<head>
<title>Wake up call</title>
<script type="text/javascript">
function wakeUpCall() { // Function is defined here
setTimeout(aa("ok"), 5000);
}
function aa(bb) {
alert(bb);
}
</script>
</head>
<body bgcolor="lightblue">
<form>
<input type="button"
value="Wake me"
onclick="wakeUpCall()">
</form>
</body>
</html>
function wakeUpCall() { // Function is defined here
setTimeout(function(){ alert("ok");}, 5000);
}
You are trying to do it the wrong way.
You have to use a callback for the setTimeout:
setTimeout(function()
{
// actual code here
}, 5000);
Mike has provided in his answer - that you could use an evaluatable string:
setTimeout('/* actual code here */', 5000);
But that is strongly discouraged, use his other example - passing the callback function as a reference and invoking callback arguments.
You have to take in mind, though, that if you are going with callback arguments, see this section of MDN article. The callback arguments aren't supported in all browsers.
Personally, I'd suggest going with plain old callbacks, because that's how the setTimeout is meant to be used.
Just for your information:
The reason why your snippet isn't working for you, is, because:
setTimeout(aa('ok'), 5000);
// aa('ok') here is executed, and returns its value, so, in the end, you pass the returned value of aa inside the Timeout.
// and, nor alert alert, nor your function have a "return" statement, so they both will return always undefined.
// that translates to:
setTimeout(undefined, 5000); // and, that does nothing
What if you would do it like this:
<html>
<head>
<title>Wake up call</title>
<script type="text/javascript">
function wakeUpCall() { // Function is defined here
setTimeout('aa("ok");', 5000);
}
function aa(bb) {
alert(bb);
}
</script>
</head>
<body bgcolor="lightblue">
<form>
<input type="button"
value="Wake me"
onclick="wakeUpCall()">
</form>
</body>
</html>
Notice I have quoted the statement to execute in the setTimeout function. It those quotes confuse you, I think this is a good resource to take a look at: https://developer.mozilla.org/en-US/docs/DOM/window.setTimeout
Another way to do it, I just learned from the resource above, is like this:
function wakeUpCall() { // Function is defined here
setTimeout(aa, 5000, "Your tekst here");
}
Use anonymous functions for this.
<html>
<head>
<title>Wake up call</title>
<script type="text/javascript">
function wakeUpCall() { // Function is defined here
setTimeout(function(){aa("ok");}, 5000);
}
function aa(bb) {
alert(bb);
}
</script>
</head>
<body bgcolor="lightblue">
<form>
<input type="button"
value="Wake me"
onclick="wakeUpCall()">
</form>
</body>
</html>
I'm trying to create a interval call to a function in jQuery, but it doesn't work! My first question is, can I mix common JavaScript with jQuery?
Should I use setInterval("test()",1000); or something like this:
var refreshId = setInterval(function(){
code...
}, 5000);
Where do I put the function that I call and how do I activate the interval? Is it a difference in how to declare a function in JavaScript compared to jQuery?
To write the best code, you "should" use the latter approach, with a function reference:
var refreshId = setInterval(function() {}, 5000);
or
function test() {}
var refreshId = setInterval(test, 5000);
but your approach of
function test() {}
var refreshId = setInterval("test()", 5000);
is basically valid, too (as long as test() is global).
Note that there is no such thing really as "in jQuery". You're still writing the Javascript language; you're just using some pre-made functions that are the jQuery library.
First of all: Yes you can mix jQuery with common JS :)
Best way to build up an intervall call of a function is to use setTimeout methode:
For example, if you have a function called test() and want to repeat it all 5 seconds, you could build it up like this:
function test(){
console.log('test called');
setTimeout(test, 5000);
}
Finally you have to trigger the function once:
$(document).ready(function(){
test();
});
This document ready function is called automatically, after all html is loaded.
I have written a custom code for setInterval function which can also help
let interval;
function startInterval(){
interval = setInterval(appendDateToBody, 1000);
console.log(interval);
}
function appendDateToBody() {
document.body.appendChild(
document.createTextNode(new Date() + " "));
}
function stopInterval() {
clearInterval(interval);
console.log(interval);
}
<!DOCTYPE html>
<html>
<head>
<title>setInterval</title>
</head>
<body>
<input type="button" value="Stop" onclick="stopInterval();" />
<input type="button" value="Start" onclick="startInterval();" />
</body>
</html>
jQuery is just a set of helpers/libraries written in Javascript. You can still use all Javascript features, so you can call whatever functions, also from inside jQuery callbacks.
So both possibilities should be okay.
setInterval(function() {
updatechat();
}, 2000);
function updatechat() {
alert('hello world');
}