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Firefox - Event Path is undefined [duplicate]

When I run event.path[n].id in Firefox, I get this error. It works in other browsers.
event.path undefined

The path property of Event objects is non-standard. The standard equivalent is the composedPath method. But it was new when the question was asked (2016); it's well-established as of this update in January 2023.
So you may want to try composedPath and fall back to path (or just use composedPath now it's established):
// Written in ES5 for compatibility with browsers that weren't obsolete
// yet when the question was posted, although they are now
var path = event.composedPath ? event.composedPath() : event.path;
if (path) {
// You got some path information
} else {
// This browser doesn't supply path information
}
Obviously that won't give you path information if the browser doesn't supply it, but it allows for both the old way and the new, standard way, and so will do its best cross-browser.
Example:
// Written in ES5 for compatibility with browsers that weren't obsolete
// yet when the question was posted, although they are now
document.getElementById("target").addEventListener("click", function (e) {
// Just for demonstration purposes
if (e.path) {
if (e.composedPath) {
console.log("Supports `path` and `composedPath`");
} else {
console.log("Supports `path` but not `composedPath`");
}
} else if (e.composedPath) {
console.log("Supports `composedPath` (but not `path`)");
} else {
console.log("Supports neither `path` nor `composedPath`");
}
// Per the above, get the path if we can, first using the standard
// method if possible, falling back to non-standard `path`
var path = event.composedPath ? event.composedPath() : event.path;
// Show it if we got it
if (path) {
console.log("Path (" + path.length + ")");
Array.prototype.forEach.call(path, function(entry) {
console.log(entry === window ? "window" : entry.nodeName);
});
}
});
.as-console-wrapper {
max-height: 100% !important;
}
<div id="target">Click me</div>
According to MDN, all major browsers support composedPath as of January 2023. Chrome (and other Chromium-based browsers) supported both path (it was a Chrome innovation) and composedPath until v109 when path was removed. (The obsolete browsers IE11 and Legacy Edge [Microsoft Edge prior to v79 when it became a Chromium-based browser] didn't support either of them.)
If you ran into a browser that doesn't support either of them, I don't think you can get the path information as of when the event was triggered. You can get the path via e.target.parentNode and each subsequent parentNode, which is usually the same, but of course the point of composedPath is that it's not always the same (if something modifies the DOM after the event was triggered but before your handler got called).

You can create your own composedPath function if it's not implemented in the browser:
function composedPath (el) {
var path = [];
while (el) {
path.push(el);
if (el.tagName === 'HTML') {
path.push(document);
path.push(window);
return path;
}
el = el.parentElement;
}
}
The returned value is equivalent to event.path of Google Chrome.
Example:
document.getElementById('target').addEventListener('click', function(event) {
var path = event.path || (event.composedPath && event.composedPath()) || composedPath(event.target);
});

This function serves as a polyfill for Event.composedPath() or Event.Path
function eventPath(evt) {
var path = (evt.composedPath && evt.composedPath()) || evt.path,
target = evt.target;
if (path != null) {
// Safari doesn't include Window, but it should.
return (path.indexOf(window) < 0) ? path.concat(window) : path;
}
if (target === window) {
return [window];
}
function getParents(node, memo) {
memo = memo || [];
var parentNode = node.parentNode;
if (!parentNode) {
return memo;
}
else {
return getParents(parentNode, memo.concat(parentNode));
}
}
return [target].concat(getParents(target), window);
}

Use composePath() and use a polyfill for IE:
https://gist.github.com/rockinghelvetica/00b9f7b5c97a16d3de75ba99192ff05c
include above file or paste code:
// Event.composedPath
(function(e, d, w) {
if(!e.composedPath) {
e.composedPath = function() {
if (this.path) {
return this.path;
}
var target = this.target;
this.path = [];
while (target.parentNode !== null) {
this.path.push(target);
target = target.parentNode;
}
this.path.push(d, w);
return this.path;
}
}
})(Event.prototype, document, window);
and then use:
var path = event.path || (event.composedPath && event.composedPath());

I had the same issue. I need the name of the HTML element. In Chrome I get the name with path. In Firefox I tried with composedPath, but it returns a different value.
For solving my problem, I used e.target.nodeName. With target function you can retrieve the HTML element in Chrome, Firefox and Safari.
This is my function in Vue.js:
selectFile(e) {
this.nodeNameClicked = e.target.nodeName
if (this.nodeNameClicked === 'FORM' || this.nodeNameClicked === 'INPUT' || this.nodeNameClicked === 'SPAN') {
this.$refs.singlefile.click()
}
}

Is this "DI" structure impossible, or should I look for a bug?

Explanation:
As a personal project, I'm trying to create my own lightweight version of Dependency Injection for JavaScript - Some would probably disagree with calling this DI because it has no interfaces, but I arrived at the conclusion that interfaces were overkill in JS since we can so easily type check. I have looked at the source of Angular, but I just feel like the complexity there may be overkill for my projects, and I'm interested in attempting my own for a learning experience anyway.
Question:
My question is, fundamentally, is the syntax I'm trying to implement impossible or not?
I'll explain my goal for the syntax, then provide the error and code snippet, and below that I'll post the full code.
Goal for Syntax:
I'd like the creation of a component, and injection of dependencies to work like this, where everything is a component, and anything can be a dependency. I created scope with a string path, using "/scopeName/subScopeName:componentName" to select a scope, so that code users can select the scope while defining the component in a simple way, using a ":" to select a component from the scope.
var JHTML = new Viziion('JHTML');
JHTML.addScope('/generate');
/* ...snip - see full code for the process component - snip ... */
JHTML.addComponent('/generate:init', function (jsonInput, process) {
var html = process(jsonInput);
return html;
}).inject([null, '/generate:process']);
The inject function just takes an array of component paths in the order the component's arguments are expected. null can be used to skip, allowing direct argument input instead, as shown above.
I also have something I call hooks, which are components stored in a certain place, and then there's a function returnUserHandle which will return an object consisting of just the hooks, so all of the functions are hidden in closures, and you can feed the code user just the usable methods, clean and easy, and can produce the final product as a library without the wiring, no need for my DI framework as a dependency. Hopefully that makes sense.
Error:
Right now, running the code (which is a very simple library to generate HTML by parsing a JSON structure) I get the error that process is undefined in the line var html = process(jsonInput);. I was having trouble understanding whether this is a fundamental design problem, or just a bug. Maybe this syntax is not possible, I'm hoping you can tell me.
Code:
Here's the code, and a link to the JS Bin.
/* Dependency Injection Framework - viziion.js */
function Viziion(appName) {
if (typeof appName == 'string') {
var that = this;
this.name = appName;
this.focus = null;
this.scope = {
'/': {
'subScopes': {},
'components': {}
}
};
this.hooks = {};
this.addScope = function(scopeName) {
if (typeof scopeName == 'string') {
var scopeArray = scopeName.split('/');
var scope = that.scope['/'];
for (var i = 0; i < scopeArray.length; i++) {
if (scopeArray[i] !== "") {
if (scope.subScopes[scopeArray[i]]) {
scope = scope.subScopes[scopeArray[i]];
} else {
scope.subScopes[scopeArray[i]] = {
'subScopes': {},
'components': {}
};
}
}
}
} else {
throw 'Scope path must be a string.';
}
return that;
};
this.addComponent = function(componentName, func) {
if (typeof componentName == 'string') {
var scopeArray = componentName.split(':');
if (scopeArray.length == 2) {
var scope = that.scope['/'];
var scopeName = scopeArray[1];
scopeArray = scopeArray[0].split('/');
for (var i = 0; i < scopeArray.length; i++) {
if (scopeArray[i] !== "") {
if ((i + 1) === scopeArray.length) {
scope.components[scopeName] = func;
that.focus = scope.components[scopeName];
} else if (scope.subScopes[scopeArray[i]]) {
scope = scope.subScopes[scopeArray[i]];
} else {
throw 'Scope path is invalid.';
}
}
}
} else {
throw 'Path does not include a component.';
}
} else {
throw 'Component path must be a string1.';
}
return that;
};
this.returnComponent = function(componentName, callback) {
if (typeof componentName == 'string') {
var scopeArray = componentName.split(':');
if (scopeArray.length == 2) {
var scope = that.scope['/'];
var scopeName = scopeArray[1];
scopeArray = scopeArray[0].split('/');
for (var i = 0; i < scopeArray.length; i++) {
if (scopeArray[i] !== "") {
if ((i + 1) === scopeArray.length) {
//console.log('yep1');
//console.log(scope.components[scopeName]);
callback(scope.components[scopeName]);
} else if (scope.subScopes[scopeArray[i]]) {
scope = scope.subScopes[scopeArray[i]];
} else {
throw 'Scope path is invalid.';
}
}
}
} else {
throw 'Path does not include a component.';
}
} else {
throw 'Component path must be a string2.';
}
};
this.addHook = function(hookName, func) {
if (typeof hookName == 'string') {
that.hooks[hookName] = func;
that.focus = that.hooks[hookName];
} else {
throw 'Hook name must be a string.';
}
return that;
};
this.inject = function(dependencyArray) {
if (dependencyArray) {
var args = [];
for (var i = 0; i < dependencyArray.length; i++) {
if (dependencyArray[i] !== null) {
that.returnComponent(dependencyArray[i], function(dependency) {
args.push(dependency);
});
}
}
console.log(that.focus);
that.focus.apply(null, args);
return that;
}
};
this.returnUserHandle = function() {
return that.hooks;
};
} else {
throw 'Viziion name must be a string.';
}
}
/* JSON HTML Generator - A Simple Library Using Viziion */
var JHTML = new Viziion('JHTML');
JHTML.addScope('/generate');
JHTML.addComponent('/generate:process', function(children) {
var html = [];
var loop = function() {
for (var i = 0; i < children.length; i++) {
if (children[i].tag) {
html.push('<' + tag + '>');
if (children[i].children) {
loop();
}
html.push('</' + tag + '>');
return html;
} else {
throw '[JHTML] Bad syntax: Tag type is not defined on node.';
}
}
};
}).inject();
JHTML.addComponent('/generate:init', function(jsonInput, process) {
console.log(process);
var html = process(jsonInput);
return html;
}).inject([null, '/generate:process']);
JHTML.addHook('generate', function(jsonInput, init) {
var html = init(jsonInput);
return html;
}).inject([null, '/generate:init']);
handle = JHTML.returnUserHandle();
/* HTML Generator Syntax - Client */
var htmlChunk = [{
tag: '!DOCTYPEHTML'
}, {
tag: 'html',
children: [{
tag: 'head',
children: []
}, {
tag: 'body',
children: []
}]
}];
console.log(handle.generate(htmlChunk));

is the syntax I'm trying to implement impossible or not?
It's absolutely possible, and I'm sure with a bit of bugfixing it'd work just fine.
What you're describing is essentially the same as Asynchronous Module Definition (AMD) which is used extensively for handling code dependencies.
Rather than continuing to pursue your own version of the same concept, I recommend that you give requirejs a try and follow the existing standards with your projects.

How to build a namespace-like string using chained variables

This is a strange one, but I'm exploring it to see if it's possible.
Let's say that I have a .NET application where I am using PubSub. I want a way to define the topic string using chained objects (not functions). The goal is to allow me a way of defining strings that lets me to take advantage of Visual Studio's IntelliSense and reduce the likelihood of spelling errors.
Here's an example:
/* Manual way */
var topic = "App.Navigation.CurrentItem"
/* Desired Solution */
// ... define the objects here ...
var topic = App.Navigation.CurrentItem;
console.log(topic); // "App.Navigation.CurrentItem"
var topic2 = App.Footer.CurrentItem;
console.log(topic2); // "App.Footer.CurrentItem"
I'd like each object to be responsible for outputing it's own value, and have the chaining process responsible for joining itself to the previous chained object via a predefined separator (in my case, a period [.]).
I've been playing with JavaScript getter syntax, but I'm curious if there's a better way.
Has anyone done something like this before, and if so, how did you solve it?

You're requirements aren't totally clear to me, but are you looking for something like this?
function namespace(ns) { this._ns = ns; }
namespace.prototype.toString = function() {return this._ns};
namespace.prototype.extend = function(suffix) {
return new namespace(this._ns + "." + suffix)
};
Usage:
App = new namespace('App');
App.Navigation = App.extend('Navigation');
App.Navigation.CurrentItem = App.Navigation.extend('CurrentItem');
console.log(App.Navigation.CurrentItem.toString()); // "App.Navigation.CurrentItem"

This is what I ended up with after reviewing StriplingWarrior's answer:
function Namespace(name, config) {
if (typeof name === "object") {
config = name;
name = null;
}
config = config || {};
this._ns = name;
this.define(config);
}
Namespace.prototype.toString = function() { return this._ns };
Namespace.prototype.define = function(config, base) {
base = base || this;
for (key in config) {
var name = (base._ns) ? base._ns + "." + key : key;
base[key] = new Namespace(name);
base.define(config[key], base[key]);
}
return base;
};
Usage:
var App = new Namespace("App", {
Navigation: {
Items: {
Current: {}
}
},
Content: {},
Footer: {
Items: {
Current: {}
}
}
});
console.log(App.toString()); // App
console.log(App.Navigation.Items.Current.toString()); // App.Navigation.Items.Current
console.log(App.Footer.toString()); // App.Footer
I also wrote a convenience method to reduce the toString():
function NS(namespace) {
return namespace.toString();
}
console.log(NS(App.Navigation.Items.Current));
Thanks again to StriplingWarrior for the the help!

How to get CSS class property in Javascript?

.test {
width:80px;
height:50px;
background-color:#808080;
margin:20px;
}
HTML -
<div class="test">Click Here</div>
In JavaScript i want to get margin:20px

For modern browsers you can use getComputedStyle:
var elem,
style;
elem = document.querySelector('.test');
style = getComputedStyle(elem);
style.marginTop; //`20px`
style.marginRight; //`20px`
style.marginBottom; //`20px`
style.marginLeft; //`20px`
margin is a composite style, and not reliable cross-browser. Each of -top -right, -bottom, and -left should be accessed individually.
fiddle

The accepted answer is the best way to get the computed values. I personally needed the pre-computed value. Say for instance 'height' being set to a 'calc()' value. I wrote the following jQuery function to access the value from the style sheet. This script handles nested 'media' and 'supports' queries, CORS errors, and should provide the final cascaded precomputed value for accessible properties.
$.fn.cssStyle = function() {
var sheets = document.styleSheets, ret = [];
var el = this.get(0);
var q = function(rules){
for (var r in rules) {
var rule = rules[r];
if(rule instanceof CSSMediaRule && window.matchMedia(rule.conditionText).matches){
ret.concat(q(rule.rules || rule.cssRules));
} else if(rule instanceof CSSSupportsRule){
try{
if(CSS.supports(rule.conditionText)){
ret.concat(q(rule.rules || rule.cssRules));
}
} catch (e) {
console.error(e);
}
} else if(rule instanceof CSSStyleRule){
try{
if(el.matches(rule.selectorText)){
ret.push(rule.style);
}
} catch(e){
console.error(e);
}
}
}
};
for (var i in sheets) {
try{
q(sheets[i].rules || sheets[i].cssRules);
} catch(e){
console.error(e);
}
}
return ret.pop();
};
// Your element
console.log($('body').cssStyle().height);

Using jQuery:
$('.class').css( "backgroundColor" );

Another approach (still experimental) could be computedStyleMap:
const computedStyleMap = document.getElementById('my-id').computedStyleMap();
computedStyleMap.get('overflow-x'); // {value: 'scroll'}
computedStyleMap.has('padding-right'); // false
computedStyleMap.entries(); // Iterator {}

I've just released an npm package for this purpose exactly. You can find it here on npm or github:
npm: https://www.npmjs.com/package/stylerjs
github: https://github.com/tjcafferkey/stylerjs
you would use it like so
var styles = styler('.class-name').get(['height', 'width']);
and styles would equal
{height: "50px", width: "50px"}
So you could just get the values like so
var height = styles.height;

open javascript library to do the same thing as symbolset

I was planning on creating my own symbol font for use on my website and I had initially intended on using ligatures and OT but support is spotty at best, and non-existant for older browsers, especially IE (I know, big surprise). I then started taking a close look at how SymbolSet works. It's actually pretty clever and while it would be easy for me to change a couple array variables and be done with it, the javascript is proprietary and I can't use it without permission. I'd love to be able to create my own symbol fonts a la SymbolSet but I'd need an open javascript file to let me do this. Are there any open jQuery plug-ins or javascript libraries that do this?

I have found this http://labs.adamdscott.com/ligatures/ligaturejs.html. Basically it walks the dom, and replaces the known letter combinations with ligatures. I've modified the script to use native ligature support when available:
// ligature.js v1.0
// http://code.google.com/p/ligature-js/
// with modifications by sabof
var ligature = (function() {
var testDiv = document.createElement('div'),
nativeLigatureSupport = testDiv.style.textRendering !== undefined;
if (nativeLigatureSupport) {
return function (node, extended) {
if (!node) {
ligature(document.body, extended);
} else {
node.style.textRendering = 'optimizeLegibility';
}
}
}
return function(node, extended) {
if (!node) {
ligature(document.body, extended);
} else {
if (node.nodeType == 3 && node.parentNode.nodeName != 'SCRIPT') {
node.nodeValue = node.nodeValue
.replace(/ffl/g, 'ffl')
.replace(/ffi/g, 'ffi')
.replace(/fl/g, 'fl')
.replace(/fi/g, 'fi')
.replace(/ff/g, 'ff')
.replace(/ij/g, 'ij')
.replace(/IJ/g, 'IJ');
if (extended) {
node.nodeValue = node.nodeValue
.replace(/ae/g, 'æ')
.replace(/A[Ee]/g, 'Æ')
.replace(/oe/g, 'œ')
.replace(/O[Ee]/g, 'Œ')
.replace(/ue/g, 'ᵫ')
.replace(/st/g, 'st');
}
}
if (node.childNodes) {
for (var i=0; i < node.childNodes.length; i++) {
ligature(node.childNodes.item(i), extended);
}
}
}
};
}());