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Found 829 results

  1. I copied the code straight from https://www.w3schools.com/nodejs/shownodejs_cmd.asp?filename=demo_events_open open.js var fs = require('fs'); var readStream = fs.createReadStream('./demofile.txt'); /*Write to the console when the file is opened:*/ readStream.on('open', function () { console.log('The file is open'); }); Upon executing "node open.js" in the terminal, "The file is open" appears in the terminal, then the program terminates. It always happens, even if I don't have demofile.txt open in Notepad or any other program. Not sure why this is happening? When I instead use the string 'close', the console never prints anything out, regardless as to demofile.txt is open or closed. This behavior has happened on both my Windows machine and Raspberry Pi. Tried putting the above code inside a http.createServer statement, but then I get no output at all in the console. Although I suppose that would be unnecessary.
  2. BACKGROUND I have created two functions both of which have been tested and function as expected -- so well, in fact, that one of them can be used to enhance the output of the other. The problem arises when I seek to call these functions with separate button alerts provided below in the order given. Both functions are defined in a jQuery ready statement. BUTTON ALERTS <script> var num = 5; </script> <button onclick="alert(num.annotate('sec'));">Alert!</button> <script> var sec_num = 59039; </script> <button onclick="alert(secTranslate(sec_num));">Alert!</button> DILEMMA: Although the first button-alert works, the second fails with the following error message: "ReferenceError: secTranslate is not defined." with a reference to the onclick attribute. QUESTION: How does one explain this phenomenon? Roddy
  3. QUESTION: Does Javascript called from a cached file behave the same as Javascript called in a freshly loaded file? Roddy
  4. DILEMMA: I have a fairly complex JSON object that is introduced via an AJAX call. Unfortunately, my control panel tells me that it is undefined. Is this because it has no value? Or, is it because I do not know how to read the value properly? {"lastVisits"[{"firstVisit":{"prettyDate":"Monday, May 14, 2018"}}]} The name of the variable into which it is read is visitor_data. Am I reading the value of correctly? visitor_data.lastVisits[0].firstVisit.prettyDate Roddy
  5. DILEMMA: Visitors to the mainpage of my website can fill the middle section of the page from the page's navigation bar in either of two ways. Both ways employ Javascript: one, copy a div already on the page into another div on the same page; and two, copy the contents of a div on a another page into same. What I would like to do now is to copy the contents of a div already on the page with a call from the contents of a div that was previously on another page. QUESTION: How does one get a div to replace its own content when the div whose contents needs to be replaced has been filled with content from another page? Roddy
  6. The DILEMMA: Recently I discovered how to enable responsive design on my website's main page. Although the page itself is now responsive, the splash panels that are associated with it are largely dysfunctional. Having experimented in various ways to make these latter responsive as well, I have decided to simply eliminate them on mobile devices. What is the best way to do this? Already I have combined PHP and Javascript to suppress the splash panels in the same session. So, my question is what is the best way to recognize any mobile device? Roddy
  7. BACKGROUND: Working with Matomo has compelled me to dig deeper into the way that information gets passed over the internet. Up until now I have assumed that I can pass just about anything in a query string. In fact, this is exactly what I have been doing. What I am beginning to realize is that the PHP $_POST and $_GET variables have been doing work of which I was not aware. I have come to this conclusion with my new encounter of the encodeURI(), encodeURIComponent(), decodeURI(), and decodeURIComponent() functions. Indeed, I have read that no information can be passed in an HTTPRequest that is not in ASCII format. Is this true? QUESTION: Is it true that when working with PHP the values of PHP HTTPRequests are automatically URL encoded and URL decoded, and that when working with Javascript the same values must be manually encoded and decoded? Roddy
  8. Hello I have the following javascript code.It is suppose to execute when the html page is done loading but in stead it executes and then nothing happend (the page seems like it is loading something but nothing ever happens) Here is my code : function LoadXML() { if(window.XMLHttpRequest) { var xmlhttp = new XMLHttpRequest(); } else{ var xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.onreadystatechange = function () { if (this.readyState == 0) { alert("im here 0"); } if (this.readyState == 1) { alert("im here 1"); } if (this.readyState == 2) { alert("im here 2"); } if (this.readyState == 3) { alert("im here 3"); } if (this.readyState == 4) { alert("im here 4"); PopulateImages(this); } }; xmlhttp.open("GET", "person.xml", true); xmlhttp.send(); } Feels like I created an infinite loop. The alert message is for debugging purposes. I get the alert message "im here 1"(not 0,2,3,4 just 1) and then the page just keeps on loading and loading and nothing is happening. Cannot open developer tools to check what code is bugging out(if I do than no resources at yet been loaded so there is nothing I can check to try and figure out the problem). I know the code will have worked if my PopulateImages function is called but it is never called.
  9. I'm using somewhat unusual navigation, as seen here. When a user mouses over the bars, they slide out into view. All of that is working fine. The problem is, I cannot find the CSS to make the buttons align left of the edge of the screen (as seen in the image), regardless of the display dimensions. I originally tried: <style> #container {width: 600px; height: 25px; position: relative;} #bar0, #bar1, #bar2, #bar3, #bar4, #bar5 {position: absolute; left: -340px;}"; </style> Which worked perfectly. But only on my screen. I thought that position:absolute inside position:relative would work regardless of screen dimensions, but I was obviously wrong. I then tried several variations on dynamically adjusting the screen width in the container <div> with a function that runs onload: function populateArrays() { // populate arrays for (i = 0; i <= 5; i++) { position[i] = -340; bar[i] = document.getElementById("bar" + i.toString()); id[i] = i; } // Add a dynamically built style sheet var sheet = document.createElement('style'); var sWidth = screen.width; var lWidth = sWidth - 1024 // 1024px is width of the page body. The result, 342, works perfectly at my resolution of 1366: 1366 - 1024 = 342 (I use -342). sheet.innerHTML = "#container {width: " + sWidth + "px; height: 25px; position: relative;} #bar0, #bar1, #bar2, #bar3, #bar4, #bar5 {position: absolute; left: " + -(lWidth) + "px;}"; document.body.appendChild(sheet); } But this also did not work. Perhaps I should be using a formula other than screen.width - 1024 = -(lWidth)? All I know is it doesn't work at other resolutions. What is the correct way to align the images to the far left, partially (mostly) off screen, regardless of dimensions? I've lost an entire day's work to this. Thank you very much
  10. i want to build a bar chart with chartJS and database mysql with two different query, but bar chart not showing. can anyone help me to correct the code? this my query and javascript: <?php $a = mysqli_query("select count(a) as total1 from tbl"); $b = mysqli_query("select count(b) as total2 from tbl"); ?> <body> <div> <canvas id="chart"></canvas> </div> <script> var ctx = document.getElementById("chart"); var chartdata = { labels: 'CHART', datasets: [{ label: "A", data: [<?php while ($data1 = mysqli_fetch_array($a)) {echo '"''.$data1['total1'].'",';}?>], backgroundColor: "#000000" },{ data: [<?php while ($data2 = mysqli_fetch_array($b)) {echo '"''.$data2['total2'].'",';}?>], backgroundColor: "#ffffff" }] }; var chart = new Chart(ctx, { type: 'bar', data: chartdata }); </script> </body>
  11. Please find below the Javascript insertion <script> tag that Matomo uses to track user behavior on a webpage. <!-- Matomo --> <script type="text/javascript"> var _paq = _paq || []; _paq.push(['trackPageView']); _paq.push(['enableLinkTracking']); (function() { var u="//{$PIWIK_URL}/"; _paq.push(['setTrackerUrl', u+'piwik.php']); _paq.push(['setSiteId', {$IDSITE}]); var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s); })(); </script> <!-- End Matomo Code --> I would like to clarify the meaning of the final line of the above function -- namely, g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s); QUESTION ONE: Can the script attributes async and defer work indepedently of each another? What is the purpose of each and does their role change when they are imlpemented together? QUESTION TWO: Given the statement s=d.getElementsByTagName('script')[0]; does the statement s.parentNode.insertBefore(g,s); read: "Find the parent node of s and prepend g before s where s is the first node of all script nodes within the document including the node containing this function"?
  12. Ok, so I have 4 combo boxes with $Year, $Month, $Type, $extension to create file name of URL. http://www.myOrg.Org/Articles/$Month + $Year + MyOrg + $Type . $extension This is what I have (doing only 1 variable - Year). <form> Select the year: <select id="mySelect"> <option>2018</option> <option>2017</option> <option>2016</option> <option>2015</option> </select> Select the month: <select id="mySelect1"> <option>January</option> <option>February</option> <option>March</option> <option>April</option> <option>May</option> <option>June</option> <option>July</option> <option>August</option> <option>September</option> <option>October</option> <option>November</option> <option>December</option> </select> Select Article or Calendar: <select id="mySelect2"> <option>Article</option> <option>Calendar</option> </select> Select PDF, Word or Webpage: <select id="mySelect3"> <option>pdf</option> <option>doc</option> <option>htm</option> </select> <br><br> <input type="button" onclick="myFunction()" value="Click Me!"> </form> <a id="myLink" href="http://www.myOrg.org/Article/April 2018 myOrg.pdf">Current Article</a> <script> function myFunction() { var obj = document.getElementById("mySelect"); var obj1 = document.getElementById("mySelect1"); var obj2 = document.getElementById("mySelect2"); var obj3 = document.getElementById("mySelect3"); document.getElementById("myLink").innerHTML = "New Link"; document.getElementById("myLink").href = "http://www.myOrg.org/Article/" + obj1.options[obj1.selectedIndex].text + " " + obj.options[obj.selectedIndex].text + " " + obj2.options[obj2.selectedIndex].text + "." + obj3.options[obj3.selectedIndex].text; document.getElementById("myLink").target = "_blank"; } </script> Works but now I want to have some if then statements. Instead of pdf, doc and htm I want to show PDF File, Word Document and Webpage but when it inserts it into the address is needs to be pdf, doc and htm. But if Calendar is selected it needs to be docx not doc. So....kinda stuck at this point.
  13. Hi everyone, A few weeks ago, Douglas Lowder from Salesforce made a brilliant talk about his port of React Native for Apple Tv. I was thinking that it could interest some here to see him describes how he did it. Thanks!
  14. This seems so simple: var aC = document.getElementById("arrowCanvas"); var context = aC.getContext("2d"); var img = document.getElementById("arrowImage"); context.drawImage(img, 225, 225); context.rotate(90 * Math.PI / 180); But the canvas never rotates. Also tried: var aC = document.getElementById("arrowCanvas"); var context = aC.getContext("2d"); var img = document.getElementById("arrowImage"); context.rotate(90 * Math.PI / 180); context.drawImage(img, 225, 225); But here, the canvas never even shows up. I could use some help with the correct syntax. Thank you!
  15. I'm having a problem determining if a given control has focus. It seems to me that: if (form.password.focus() == true) ... should tell me if the form's password control has focus. But, it's returning "false" even while I'm typing into the control. So, what is the correct way to determine whether a control has focus? Thank you!
  16. I need to create variable names in a loop (part of this seems to be working) and then get 26 of the 39 variables to perform simple math (for example: variable -= 10). Getting the variables recognized as variables, and not text, seems to be the issue. This works properly, it accesses 13 canvases named canvas1 through canvas13: for (i = 1; i < 14; i++) { c = document.getElementById("canvas" + i.toString()); context = c.getContext("2d"); ... } However, when I try to dynamically create canvas names, and dynamically create 2 variables in the same line, the variables are created as text. for (i = 1; i < 14; i++) { document.getElementById('canvas' + i).style.filter = "brightness((bright" + i + " -= 10)%) contrast((cont" + i + " -= 10)%)"; } Probably a dozen variations on this theme have failed. In a nutshell, the variables bright1 and cont1 through bright13 and cont13 are not recognized as variables that can be manipulated with math, they're recognized as text. Right now I'm typing out 13 lines of code: document.getElementById('canvas1').style.filter = "brightness(" + (bright1 -= 10) + "%) contrast(" + (cont1 -= 10) + "%)"; ... document.getElementById('canvas13').style.filter = "brightness(" + (bright13 -= 10) + "%) contrast(" + (cont13 -= 10) + "%)"; which is inefficient, to say the least. So, what is the proper syntax to use so that bright1 through bright13 and cont1 through cont13 are variables instead of text? Thank you!
  17. BACKGROUND: Earlier I posted a script from Matomo that serves as a counter for page hits and various other bits of information gleaned from a user's behavior on a webpage that bears the script. Although I now understand what the code does, I would like to understand its purpose. In particular, I would like to understand the probable reason for assigning to a variable another variable with the same name. The full code is given as: <!-- Matomo --> <script type="text/javascript"> var _paq = _paq || []; _paq.push(['trackPageView']); _paq.push(['enableLinkTracking']); (function() { var u="//{$PIWIK_URL}/"; _paq.push(['setTrackerUrl', u+'piwik.php']); _paq.push(['setSiteId', {$IDSITE}]); var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s); })(); </script> <!-- End Matomo Code --> The code of interest is var _paq = _paq || []; I find this piece of code problematic for three reasons: It assumes that this variable could already exist, but I have no idea where it could come from. It it does already exist what happens to the pre-existent with the same name. How does it know which value to choose? Is there a latent selection mechanism that tells the assignment operator to choose the second value when the first is undefined? Please advise. Roddy
  18. smus

    Array cloning

    Sorry for stupid question. I can't understand the purpose of cloning an array in JS. Why do we need it? What is the difference between: let a = []; let b = a; and: let a = []; let b = a.slice(0);
  19. Although by no means fully recovered from a recent machine failure, I am back on the road in a much weakened condition. Please consider the following piece of code and correct me where my interpretation of the code is in error. <!-- Matomo --> <script type="text/javascript"> var _paq = _paq || []; _paq.push(['trackPageView']); _paq.push(['enableLinkTracking']); (function() { var u="//{$PIWIK_URL}/"; _paq.push(['setTrackerUrl', u+'piwik.php']); _paq.push(['setSiteId', {$IDSITE}]); var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0]; g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s); })(); </script> <!-- End Matomo Code --> My interpretation of same var _paq = _paq || []; _paq is an array that is initialized as empty or some preassigned value. _paq.push(['trackPageView']); Add a new element to _paq whose key-value pair is 'trackPageView' : undefined var u="//{$PIWIK_URL}/"; Create a variable called called u and assign to it the following string "// + some.domain.name + /". _paq.push(['setTrackerUrl', u+'piwik.php']); Add a new element to _paq whose key-value pair is 'setTrackerUrl' and u + piwik.php, respectively. var d=document, g=d.createElement('script'),s=d.getElementsByTagName('script')[0]; Create three variables named d, g and s whose values are d: the DOM document g: the name of a newly created element called 'script' s: an empty index array called 'script' g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s); The resulting script tag should appear as follows: <script text='javascript' async='true' defer='true' src= 'u + piwik.js'></script> function()(); Run the function upon loading the document in which it is contained. Roddy
  20. Hello I need to get the value of a CSS Filter, Hue in this case, that's currently being applied to a canvas. I tried this: var hue = document.getElementById('canvas1').style.filter('hue-rotate'); and it did not work, several variations on that theme also failed. What is the correct syntax? Thank you very much PS: this could apparently also work var hue = getComputedStyle(canvas1).filter But it will not retrieve just the hue. Thank you
  21. I am going to create a Extension for internet explorer but i am not able to understand how to start creating Extension for internet explorer.
  22. I have searched in vain for an answer to this problem, but I am getting no where. Here is the issue: I have a search form that works fine as a desktop application. On mobile devices there is a problem. If a user starts typing in the search input, and then taps one of the words that pops up in predictive text (such as on an iphone), this word then fills the input. The search form returns no matches because, as I have discovered, the only thing being submitted is what the user actually typed before tapping the predictive hint. For example, if they start typing Pennsylvania but only type "Pennsy" and then tap the suggestion, the only value in the input is "Pennsy," not the whole word. I have seen some suggestions: for example, setting the input type to 'password' prevents predictive suggestions (and thus requiring the user to type out the entire term), but this also triggers hiding the text submitted (as if it were a password). I have also seen some suggest that you could use setTimeout() before ajax submits the form to the server, but this did not work either and I am not quite sure of the logic behind this solution anyway. Is there a way for javascript / jquery to "read" the value of an input that the user filled by means of tapping predictive text? Thanks in advance' reveret
  23. We had a ton of problems with React to handle our states. We adopted Redux, and after a short period we could finally just focus on producing features and not bugs Here is a video of the last meetup we did in San Francisco: Using Redux at scale. Here is the source medium article for those who cannot listen to the video: https://blog.matters.tech/10-redux-tips-from-the-trenches-55e06ed1c0a8
  24. I tried including the 'tab.html' and ‘content.html’ into my 'index.html' (using w3school code: how to include HTML, found at: https://www.w3schools.com/howto/howto_html_include.asp), but the javascript and css elements do not work. The buttons don't work as intended. Look at: https://rads-198409.appspot.com If you minimize the browser window, the tab is supposed to change to a drop-down menu, but the button does not work at all. I have checked the individual pages and they seem to work just fine, just not when they are combined. Am I doing something wrong? Could someone help? All the code I used is from w3school and I have only modified the file names (tab.html and content .html to point to the right files). Below are links to the code: Code for ‘tab.html’ - https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_topnav Code for ‘content.html’ - https://www.w3schools.com/howto/tryit.asp?filename=tryhow_js_collapsible_symbol Code for ‘index.html’ - https://www.w3schools.com/howto/tryit.asp?filename=tryhow_html_include_2
  25. I have a form written using HTML5 and CSS3, final validation is performed on submit with JavaScript. Then, the form will be sent to the server, most likely using PHP's mail() function. I don't recall how to include two items such as these in a form's action="...", I'd deeply appreciate if someone could refresh my memory! Thank you
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