JavaScript

Re: [Vanilla Javascript Newbie] How to access a function of a function from a part of code oustide this function

8-Nov-20 21:58

See JavaScript Functions[^]

Richard Deeming9-Nov-20 22:07

9-Nov-20 22:07

Working with objects - JavaScript | MDN[^]

The simplest option:

JavaScript

var Game = function(settings) {
    ... 

    this.quitGame = function(settings) {
        ...
    }
};

var settings = "blablah";
var game = new Game(settings);
...
game.quitGame(settings);

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Get image extension

Valentinor4-Nov-20 3:10

4-Nov-20 3:10

Is there a way to get the extension of an image if you know it's link? At first I thought of splitting the string with . and get the last part, but the problem with this is that there are some links that don't include the extension at the end so this is not an universal solution.
Because I know the link each time, is there something I can do with an image object (new Image), or how else can I get the extension? All the results I got were to check if it is an image but not it's extension, or the one I explained above, but that won't work in every scenarios.

This will be done in a extension for Firefox.

modified 9-Nov-20 16:23pm.

Blanksy8-Nov-20 11:12

Blanksy

8-Nov-20 11:12

mebbe something like...

file = url.split('/').pop();

Valentinor8-Nov-20 19:33

8-Nov-20 19:33

Unfortunately like I said, there are some website where the file name and the extensions is not included into the link, so there is nothing to split to get them.

But even then, if you use the built-in "Save Image As...", the browser still knows what those are, so there has to be a way to do it.

Richard Deeming8-Nov-20 21:53

8-Nov-20 21:53

The browser doesn't use the image extension; it uses the MIME-type, which is supplied in the Content-Type header.

To read this from Javascript, either the image will need to be on the same domain as your page, or the remote domain will need to set the CORS headers to allow your site to request the image.

Cross-Origin Resource Sharing (CORS) - HTTP | MDN[^]
image - How to get <img> content-type using javascript after loading - Stack Overflow[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Valentinor9-Nov-20 5:43

9-Nov-20 5:43

Richard Deeming wrote:
To read this from Javascript, either the image will need to be on the same domain as your page, or the remote domain will need to set the CORS headers to allow your site to request the image.

Because this will not work in Javascrip with all websites which we actually need, in what other language can it be done?
I do apologies, web applications is not what I normally do, but this time I have to do it and learn for the future, maybe I'll run into something similar.

Richard Deeming9-Nov-20 5:58

9-Nov-20 5:58

You'd have to write something on the server - eg: ASP.NET, PHP, etc. Basically, any server-side language that can make a HEAD request and read the headers from the response.

For example, in C#:

public static async Task<string> GetContentType(HttpClient client, string url)
{
    if (string.IsNullOrEmpty(url)) throw new ArgumentNullException(nameof(url));
    if (!Uri.TryCreate(url, UriKind.Absolute, out var uri)) throw new ArgumentException("Invalid URL", nameof(url));
    
    using (var request = new HttpRequestMessage(HttpMethod.Head, uri))
    using (var response = await client.SendAsync(request, HttpCompletionOption.ResponseHeadersRead))
    {
        response.EnsureSuccessStatusCode();
        return response.Content.Headers.ContentType.MediaType;
    }
}

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Valentinor9-Nov-20 10:31

9-Nov-20 10:31

We don't have any control over the server, this is goin to be done in a extension for Firefox. We added a new contextMenu for images only, and from that we can get the Url, but as I said in the first thread there are some websites that don't add the name and the extension directly into the link (example.com/image.jpg / example.com/someImage), so we need to find another way to get them when the user right click's on it.

Richard Deeming9-Nov-20 21:36

9-Nov-20 21:36

Once again, there may not be an image extension. You will have to use the content type.

It looks like it is possible to request extra permissions to your extension to bypass CORS restrictions for certain domains:
permissions - Mozilla | MDN[^]

But it may be easier to intercept the network requests from your extension:
Intercept HTTP requests - Mozilla | MDN[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Valentinor10-Nov-20 4:10

10-Nov-20 4:10

Richard Deeming wrote:
But it may be easier to intercept the network requests from your extension:
Intercept HTTP requests - Mozilla | MDN[^]

I'll try this and see if I manage to make something using it. I first thought this whole thing will be something easy. Smile | :)

function with OR

Member 1497891029-Oct-20 9:30

Member 14978910

29-Oct-20 9:30

Hello all,

I would like to ask you for a help. I would like make a function for add a class. For interactive map. It means there will be a few segments and ONCLICK will be ADD CLASS.

I used this code:

JavaScript

function myFunction() {
    document.getElementById("praha").className = "show";
  }

It works, but only for 1st segment.

I would like to use something like OR. I tried this:

JavaScript

function myFunction() {
    document.getElementById("praha").className = "show"; ||
    document.getElementById("stredniCechy").className = "show";
  }

JavaScript

function myFunction() {
    document.getElementById("praha"||"stredniCechy").className = "show"; 
  }

But both of them doesnt works... Could someone give me an advice and help me with it Smile | :)

?
Many thanks

Re: function with OR

Richard MacCutchan29-Oct-20 10:41

JSMAN - JavaScript Map alternative notation

29-Oct-20 10:41

Those statements do not make sense, as there is no condition test. You first need to add a test to decid which one is required, somthing like:

JavaScript

eltname = (<condition test goes here>) ? "praha" : "stredniCechy";
document.getElementById(eltname).className = "show";

The condition test is whatever you use to decide which name to use.

Member 1497706227-Oct-20 17:35

Member 14977062

27-Oct-20 17:35

Hi, I've created a small library for declaring Maps, WeakMaps or maps-like arrays. Maybe someone will find it useful.

https://www.npmjs.com/package/jsman
https://github.com/mothgears/jsman

Re: JSMAN - JavaScript Map alternative notation

Sandeep Mewara27-Oct-20 19:34

Sandeep Mewara

27-Oct-20 19:34

This is a Javascript based Q&A forum. In case you want to share your work, would suggest you to submit it as Your GitHub Project on CodeProject with details about how it is useful and can be used. Follow the guidelines and submit, it will showcase as other articles for people to read.

With current message, most will not be able find what you want to share and will be lost. Thanks!

Latest CodeProject post:
Linear Time Partition – A Three Way Split
Dynamic Programming – What, How & When

To read all my blog posts, visit: Learn by Insight...

find low distance from two matrices

costy3527-Oct-20 6:57

costy35

27-Oct-20 6:57

This alghoritm i want to use to create shape for cnc foam cutter ... so a one line need to pass all countour paths

for example:

i have 4 path with x,y points coordonates

path1=[[5,3][3,2][8,9][8,8][7,3]]

path2=[[1,9][8,4][3,6]]

path3=[[8,3][4,7][1,2][2,7][4,2][7,5]]

path4=[[4,3][1,7][9,7][8,0]]

Alghoritm need to find in primis a most low value apropriate to 0 in this case [1,2] that is in path3 point 3

After find this point...compare all points of path3 with points of all paths and find most appropiate value ... in this case [8,4] from path2 that is closest to [8,2] from path3

after find most apropiate value ...join the path3 with path 2 in pointers find

result_path=[[0,0]->[1,2][2,7][4,2][7,5]->[8,3]->[8,4][3,6]->[1,9]->[4,7]]

And after join path2 with path3 in this mode ... compare all points of result_path with points of remainder paths (path1,path4) ... and insert path find in result_path in same mode

I dont know how explain better!

Re: find low distance from two matrices

Richard MacCutchan27-Oct-20 7:14

Re: find low distance from two matrices

27-Oct-20 7:14

Is this a Javascript question or are you just looking for a generic algorithm? If the latter then please use the correct forum at Algorithms Discussion Boards[^].

costy3527-Oct-20 11:18

costy35

27-Oct-20 11:18

i put this post also in algoritms ... but ... message closed!!!

Re: find low distance from two matrices

Richard MacCutchan27-Oct-20 21:49

Converting image file format

27-Oct-20 21:49

You should post it in one place only.

Valentinor26-Oct-20 23:40

Google Map API & JavaScript Issue (Snowload Calculator) Working Model for easier troubleshooting

26-Oct-20 23:40

I am trying to make an add-on for Mozilla Firefox that will convert an image (from a given direct link) to another format and then give the user the save file pop-up.

I have tried to use JavaScript to turn the image into a canvas, and then the canvas to an image with the format wanted, but I run into the problem with canvas.toDataURL, that doesn't allow to use an image from another origin, and I get Uncaught DOMException: The operation is insecure. How else can I do this image conversion? I know it is possible to do it, because there are other add-ons that do this, but my add-on will have other specific functions for our work beside only image conversion, and we can't use those because of that.

I'm doing the testing in straight HTML, because it is easier to do it this way, then keep refreshing the add-on in browser.

Here is the code:

<!DOCTYPE html>
<html>
<head>
	<meta content="text/html;charset=utf-8" http-equiv="Content-Type">
	<meta content="utf-8" http-equiv="encoding">
</head>
<body>
<script>
window.onload = function() {
	var image = new Image();
    image.addEventListener("load", imageLoaded, false);
	image.src = "theLinkToAnImage";
};

function imageLoaded() {
	var canvas = document.createElement("canvas");
	canvas.width = this.width;
	canvas.height = this.height;
	canvas.getContext("2d").drawImage(this, 0, 0);

	var image = new Image();
	image.crossOrigin = "Anonymous";
	image.src = canvas.toDataURL("image/jpg");
	document.body.appendChild(image);
}
</script>
</body>
</html>

modified 27-Oct-20 6:59am.

Member 1497471825-Oct-20 4:31

Member 14974718

25-Oct-20 4:31

Thank you for taking the time to review my question.

I am using Google Maps API and custom JScript to be able to calculate snow loads in Tahoe Basin.

This all works as expected except for one county...El Dorado, which does not work and I have not been able to isolate the issue.

Working Page Here: http://zacharyengineering.com/snowload_calculator

***NOTE: works perfectly except for Eldorado County (South Shore Lake Tahoe) Click and you will see this error:

ERROR: The address provided appears to be in El_Dorado County county (only Placer, Washoe, Nevada, El Dorado, and Douglas counties are supported)

This is the catch-all error for when someone clicks outside of the supported area.

I can upload the JScript file if helpful...

Thanks Again, I am stumped as to how to address this error. matt

XML NodeList Java object showing null in Nashorn Javascript

shampoo7224-Oct-20 9:40

shampoo72

24-Oct-20 9:40

I'm trying to read multiple matching values of an xpath expression from an xml file in an array in Nashorn Javascript. I'm using javax.xml.xpath classes inside Nashorn to parse xml data. I'm able to read the first matching value just fine when I pass, XPathConstants.STRING to the evaluate function.

alist = xpath.evaluate(exp, input, XPathConstants.NODESET); System.out.println(alist.item[0].getNodeValue());

Its throwing this error - javax.script.ScriptException: TypeError: Cannot read property "getNodeValue" from undefined in

Any ideas why the list would have all null valued elements?

Re: XML NodeList Java object showing null in Nashorn Javascript

Richard MacCutchan24-Oct-20 21:59

Re: XML NodeList Java object showing null in Nashorn Javascript

24-Oct-20 21:59

That sounds more like Java than Javascript. And the error message is telling you that alist is most likely null because the evaluate call did not return anything.

shampoo7225-Oct-20 6:04

shampoo72

25-Oct-20 6:04

Yes. I'm using Java inside Nashorn Javascript. Here's my xml and xpath.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?> <triggers count="1"> <trigger id="TRIGGER_6" type="buildDependencyTrigger"> <properties count="2"> <property name="branchFilter" value="+:<default>"/> <property name="dependsOn" value="Project1_BuildConfig1"/> </properties> </trigger> <trigger id="TRIGGER_7" type="buildDependencyTrigger"> <properties count="2"> <property name="branchFilter" value="+:<default>"/> <property name="dependsOn" value="Project1_BuildConfig1"/> </properties> </trigger> </triggers>

/triggers/trigger[@type='buildDependencyTrigger']/properties/property[@name='dependsOn']/@value

As I mentioned, when I use XPathConstants.STRING, I do get the value from the first 'trigger' node with same xpath.

modified 25-Oct-20 12:21pm.

Re: XML NodeList Java object showing null in Nashorn Javascript

Richard MacCutchan25-Oct-20 6:14