How to make values show up in input boxes

Question

This is my first time coding, and I'm trying to create a feature on my website where after I select an item from the dropdown menu, values corresponding to that item will show up in the input boxes I created. An example is if I select "apples" from my dropdown menu, the values "1.2" and "4.00" will show up in the "Pounds" and "Cost" input boxes respectively.

I already have code written using HTML and JS for the dropdown menu and input boxes, and I have stored the data corresponding to the items in a csv file. Right now, values show up in the input boxes only because I wrote code for that in JS. Is there any way for the HTML file to read my data from a csv file and display that data in my input boxes? Below is what I have so far.

<div id="cs-element">
  <label id="cs-element-label">Elements</label>
</div>

<select onChange="dropdownTip(this.value)" name="search_type" style="margin-right:10px; margin-top:2px;">
 <option selected="selected">Choose Element</option>
 <option>Methane</option>
 <option>Ethane</option>
 <option>Propane</option>
 <option>n-Butane</option>
</select>

<div id="result"></div>

<script type="text/javascript">
 function dropdownTip(value){
   console.log(value);
    document.getElementById("myText").value="190.6";
    document.getElementById("myText1").value="45.99";
    document.getElementById("myText2").value="0.012";
 }
</script>

<div id="cs-tc" class="col-sm-4 text-center">
  <label id="cs-tc-label" class="control-label">Critical Temperature (K)</label>
 <input type="text" id="myText" value=" " class="form-control" name="cs_tc">
</div>

<div id="cs-pc" class="col-sm-4 text-center">
  <label id="cs-pc-label" class="control-label">Critical Pressure (atm)</label>
  <input type="text" id="myText1" value=" " class="form-control" name="cs_pc">
</div>

<div id="cs-acc" class="col-sm-4 text-center">
  <label id="cs-acc-label" class="control-label">Accentric Factor</label>
  <input type="text" id="myText2" value=" " class="form-control" name="cs_acc">
</div>

<script>
$(document).ready(function() {
  $.ajax({
    type: "GET",
    url: "B1_1.csv", //read csv file
    dataType: "text",
    success: function(data) {processData(data);}
   });
});

function processData(allText) {
 var allTextLines = allText.split("/\r\n|\n/");
 var headers = allTextLines[0].split(',');
 var lines = [];

 for (var i=1; i<allTextLines.length; i++) {
  var data = allTextLines[i].split(',');
  if (data.length == headers.length) {

   var tarr = [];
   for (var j=0; j<headers.length; j++) {
    tarr.push(headers[j]+":"+data[j]);
   }
   lines.push(tarr);
  }
 }
}
</script>

Answer 1

If I understand what you're asking, no, is not possible to read file from html. Using a form in html you can upload files, but the event is handled by javascript.

Answer 2

Have a look at the W3.JS library. It has a component called W3.data which allows fetching server data using JavaScript. It can be used to read the contents of JSON and CSV files.

Answer 3

Yes, of course is possible, the code you've posted is doing that, I know that initially can be confusing, but let me explain the javascript part...

<script> 
// in html you use script tag to put javascript code inside and using jquery, you // can easily modify the html page.

$(document).ready(function() { 
// this is a jquery piece of code that is calling an // ajax request

  $.ajax({
    type: "GET",
    url: "B1_1.csv", //read csv file
    dataType: "text",
    success: function(data) {processData(data);}
   });
});

function processData(allText) { 
// a method is a piece of code that you write once because you know that you will // reuse it and it makes the code more readable

 var allTextLines = allText.split("/\r\n|\n/"); 
// split is a method that takes as input a string and (in this case `allText`) //literally split the calling string in n strings storing them in an array. The //strings are splitted by the string you passed as parameter. In this case this //piece of code is simply dividing the entire text in n lines

 var headers = allTextLines[0].split(','); 
// Now is splitting the line number 1 (look for 0-indexed array on google) in many // strings
 var lines = [];

 for (var i=1; i<allTextLines.length; i++) {
 // A for loop is a loop that repeat itself n-times until a condition is no more 
 // satisfied, in this case i has to be smaller than the length of that array.
 // `var i=1` represents the starting point of the index.
 // `i<allTextLines.length` is the condition and `allTextLines.length` returns the 
 // length of the array.
 // In the end `i++` just increment i every time the loop reach the end and restart

  var data = allTextLines[i].split(',');
  if (data.length == headers.length) {
    // an if statement is a piece of code that is executed if and only if a condition 
    // is satisfied.

   var tarr = [];
   for (var j=0; j<headers.length; j++) {
    tarr.push(headers[j]+":"+data[j]);
   }
   lines.push(tarr); // The push method add to an array a new element
  }
 }
}
</script>

I tried to explain as better as I can (I'm a bad teacher, so this is training for me ahah), I hope I've helped you. If you have any doubt just ask and if you want to get more into code just lookfor tutorials on the web, because there are a lot. Maybe you're interested, I've learned javascript from here years ago.