Javascript: Difference between revisions

Revision as of 14:53, 3 March 2018

Basics

Javascript and JQuery

Formatting examples (numbers dates etc.)

 // Javascript sucks at dates.
 // d3 to the rescue!  
 var parseInitDate = d3.utcParse("%Y-%m-%dT%H:%M:%SZ");
 var initDate = parseInitDate(initial_managed_value_date);
 var initDateString = 
     initDate.getUTCFullYear() 
     +"/"+ (initDate.getUTCMonth()+1) 
     +"/"+ initDate.getUTCDate()
     + " " + initDate.getUTCHours() 
     + ":" + initDate.getUTCMinutes() 
     + ":" + initDate.getUTCSeconds();

 var rightNow = new Date;
 var initToNow_DecimalDays = parseFloat(rightNow - initDate) / 864e5;  // 86,400,000 ms/day
 var initToNow_PercentOfYear = initToNow_DecimalDays / 365.0;
 var change_in_value = (parseFloat(total_managed_value) - parseFloat(initial_managed_value))/parseFloat(initial_managed_value);

 $('#initial_managed_value').val(initial_managed_value.toFixed(2)); 
 $('#initial_managed_value_date').val(initDateString);
 $('#change_in_value').val((change_in_value*100.0).toFixed(1)+ "%");
 $('#equivalent_apr').val((change_in_value/initToNow_PercentOfYear*100.0).toFixed(1)+ "%");
 $('#total_managed_value_readonly').val(total_managed_value.toFixed(2));

Array vs Object lifetime

       // If the JSON data were an array, we would need to slice-to-clone to keep it around:
       //     var dataCopy = data.slice();
       //     updateStockData(run,dataCopy);
       // We have an object so we can pass a reference, and it will keep the object around.

Event handlers

Three basic methods:

Attach a function to an event of a specific element; charts.js example:

     var label = jQuery('<label class="btn btn-sm btn-'+color+'"></label>').appendTo(action_button_bar);
     var input = jQuery('<input class="run-'+cmd+'" type="checkbox" autocomplete="off" value="'+cycle.run+'">').appendTo(label)
     .on('change', cycle.owned? function(){
       patchPick(this.value,'{ "action" : "run-hold"       }');
     } : function() {
       patchPick(this.value,'{ "action" : "run-buy"        }');
     });
     var text = jQuery(' '+cmd+'').appendTo(label);

Add a function handler once, for a class of elements; picks.js example:

 $("input[type='checkbox'][class='run-top'    ]").change(function() { patchPick(this.value,'{ "action" : "run-move-top"   }');  });

Event delegation: Javascript takes events and "bubbles them up" through the chain of parents; set up a handler on a parent to listen for these bubbles.
At end of handler, prevent further bubbling with stopPropagation() - still finishes the current event (eg following the href of an <a>):

    var datepicker = jQuery(
      '<div class="input-group date form-inline pull-left" data-provide="datepicker" id="datepicker'+cycle.run+'">'+
        '<input type="text" class="input-sm form-control">'+
        '<div class="input-group-addon">'+
            '<span class="glyphicon glyphicon-th"></span>'+
        '</div>'+
      '</div>'
    )
    .on('changeDate', function(e){
      alert('next '+cycle.run);
      e.stopPropagation();
    })
    ;

Or use preventDefault() to stop completely:

    var datepicker_next = jQuery(
      '<a href="">My javascript action</a>'
    )
    .on('click', function(e){
      alert('next '+cycle.run);
      e.preventDefault();
    })
    ;

Debug clicks on ANY PAGE
Press F12 => Sources => Event Listener Breakpoints righthand pane => Mouse => [x] click B O O M we have it captured and can step into ANYTHING.

JWT flow

Client is easy!

   Client application                                            API
   --------                                              -----------
        |                                                      |
        |                   GET /api/employees                 |
        |----------------------------------------------------->|
        |                     403 Forbidden                    |
        |<-----------------------------------------------------|
        |                                                      |
        |                                                      |
        |                 POST /api/authenticate               |
        |     { login: "john.doe", password: "password" }      |
        |----------------------------------------------------->|
        |                      200 Success                     |
        |             { token: "my.personal.token" }           |
        |<-----------------------------------------------------|
        |                                                      |
        |                                                      |
        |                 GET /api/employees                   |
        | Header { "Authorization: Token "my.personal.token" } |
        |----------------------------------------------------->|
        |                      200 Success                     |
        |<-----------------------------------------------------|
        |                                                      |

Node.js

Node.js installation

Node create a new module

Register with npm
A one-time registration is required on a new machine if you want to publish from it: npm adduser Username: moodboom Password: (see private) Email: (this IS public) moodboom@gmail.com

Publish a node module

sudo npm install -g # keep doing this until you are happy with local install
# update version in package.json
# this creates a FULL "annotated" tag, not a "lightweight" tag that doesn't show up for [git describe] - it also removes the need for a separate commit
git tag -a 1.0.5 -m "changes include..."
git push && git push --tags  # NOTE: bitpost has a git hook to push changes all the way up to github
npm publish

Update a node module's dependencies

# make sure dependency in package.json has a carat at the beginning of its version (^x means "at least" version x)
# make sure the dependency has a new version available - completely publish it first if it is your own
# then you can simply reinstall from within the module folder to get all dependencies upgraded
sudo npm install -g

Develop several node modules at once
Convert dependencies to use local packages instead of published versions, eg: cd ~/development/mah-haus npm install -S /home/m/development/thedigitalage/rad-scripts Then reinstall everything (local dependent modules, then parent modules, pita - consider links if doing longer-term dev) sudo npm install -g Then convert back to published versions as they become available (it's up to me to stabilize and publish new module versions): cd ~/development/mah-haus npm install -S rad-scripts

auto AWS
npm install -g aws-sdk Add credentials here: C:\Users\Administrator\.aws see existing scripts, anything is possible

install bootstrap
npm install -g grunt-cli mkdir mysite && cd mysite npm install bootstrap cd node_modules/bootstrap npm install # to actually pull down dependencies grunt dist # builds and minifies so you're good to go!

Bootstrap

Single Page Application

css:

  .mdm-scrollable-div
  {
    height: 100%; 
    overflow: auto;
  }

html:

  <-- header -->

  <div class="frame" id="frame1top">
    <div class="mdm-scrollable-div">
      ...
    </div>
  </div>

  <-- footer -->

js:

  // We need to adjust layout on resize, in ready handler, and programmatically as needed.
  $(window).resize(adjustLayout).resize();

  $( document ).ready(function() {

    // We need to adjust in ready handler, on resize, and programmatically as needed
    adjustLayout();

    /* your other page load code here*/

  });

  function adjustLayout(){

      // ----------------------
      // Fundamental dimensions
      var hh = $('#theheader').outerHeight();
      var fh = $('#thefooter').outerHeight();
      var workspace_height = $(window).height() - hh - fh;
      var workspace_width = $(window).width(); 
      // ----------------------
      
      var cols = 1;
      var col_gap = 16;
      
      // Margin is based on percent of one column width, so it goes to zero before column width does.  :-)
      // Width is based on total width minus margins, then split between columns.
      var margin = ($(window).width() / cols) * .04;
      var w = ($(window).width() - (margin * (cols + 1))) / cols;
      
      var h1 = workspace_height;
      
      $('#frame1top').css({
          display:'block', 
          position:'absolute',
          left: margin * 1 + w * 0,
          top: hh,
          width: w,
          height: h1
      });
  }

Button handlers

Buttons can be represented with labels; in that case, use a click handler:

    jQuery('<label id="'+cycle.apsID+'" class="btn">MahButt</label>')
    .appendTo('#'+chartid+'-apsbar')
    .on('click', function(){
      $(location).attr('href','/v1/parameters/'+this.id+'.html');
    });

You can also get the checked state, and prevent the button from being pressed, among other things:

      jQuery('<label id="'+cycle.run+'" ...
      .on('click', function(e){
        var run = this.id;
        // Look for the (label->input)
        if (this.firstChild.checked)
        ...
        // To prevent checked/pressed state if desired:
        e.stopPropagation();
      }

Button bars are represented by labels wrapped around inputs:

    <div class="btn-group live-buttons" data-toggle="buttons"><div class="btn-group"><label class="btn"><input type="checkbox">text...

In that case use a change handler on the input:

      var label = jQuery('<label class="btn btn-sm btn-'+color+'"></label>').appendTo(action_button_bar);
      var input = jQuery('<input class="run-'+cmd+'" type="checkbox" autocomplete="off" value="'+cycle.run+'">').appendTo(label)
      .on('change', cycle.owned? function(){
        patchPick(this.value,'{ "action" : "run-hold"       }');
      } : function() {
        patchPick(this.value,'{ "action" : "run-buy"        }');
      });
      var text = jQuery('<span class="glyphicon glyphicon-'+glyph+'"></span> <span class="hidden-xs">'+cmd+'</span>').appendTo(label);

If you just need clicks from the button bar, you do NOT NEED input:

    <div class="btn-group live-buttons" data-toggle="buttons"><div class="btn-group"><label class="btn">text...

Then you can put the change handler right on the label:

    var applybar = jQuery('<div id="applybar-'+cycle.run+'" class="btn-group pull-right" data-toggle="buttons" />');
    var apply_button = jQuery('<label id="apply-'+cycle.run+'" class="btn btn-sm btn-moneygreen"><span class="glyphicon glyphicon-ok"></span><span class="hidden-xs"> Apply</span></input></label>')
    .on('click', function(e) {    
    
        // Do work

        e.stopPropagation();
    })
    .appendTo(applybar)
    ;

Programmatically pressing a button
You MUST DO TWO THINGS: Set the active class on the button/label Set the input to checked <label class="btn active"> <input type="checkbox" autocomplete="off" checked> Click me </label>

Handling the UNCHECK event on a pushbutton
Again you MUST SET BOTH active and checked STATES PROPERLY when creating the button (see above). Do not set either if the button is unpressed; set both if it is pressed. Then you can use a single change event: $("input[type='checkbox'][class='run-hold-on-buy' ]").change(function() { patchPick(this.value,'{ "action" : "'+(this.checked?'hold-on-buy-on' :'hold-on-buy-off' )+'"}'); });

Collapsible panel

Use a unique id on content div, data-target to connect panel header to content, mdm-panel-collapser so javascript can find icon, abt-scrollable-panel for margin.
HTML for each panel (starts collapsed)

    <div class="panel panel-default abt-scrollable-panel">
      <div class="panel-heading collapsed" data-toggle="collapse" data-target="#my-content-block-one">Software development skills<span class="mdm-panel-collapser text-muted glyphicon glyphicon-chevron-down pull-right"></span></div>
      <div class="collapse" id="my-content-block-one">
        <div class="mdm-panel-body">
  
         <!-- CONTENT, can include another nested panel, just add .mdm-nested-panel to class; example: -->
  
          <div class="panel panel-default mdm-scrollable-panel mdm-nested-panel">
            <div class="panel-heading collapsed mdm-job-panel-heading" data-toggle="collapse" data-target="#toshiba-job"><p><strong>Senior Developer and Offshore Manager</strong><i> - Toshiba Global Commerce Solutions, Inc.</i><span class="mdm-panel-collapser text-muted glyphicon glyphicon-chevron-up pull-right"></span></p><p><small>April 2014 – August 2015</small></p></div>
            <div class="collapse in" id="toshiba-job">
              <div class="mdm-panel-body">
                <!-- SUBCONT(IN)ENT im so funny -->
              </div>
            </div>
          </div>
          

        </div>
      </div>
    </div>

For an expanded panel, simply change icon from down to up, and add "in" to content div:

    ... glyphicon-chevron-up ...
    <div class="collapse in mdm-panel-body" id="collapseOrderItems1">

Define Javascript collapser once on load

 $('.collapse').on('hide.bs.collapse show.bs.collapse', 
   toggleCollapser
 );

CSS

   .mdm-nested-panel {
     margin-top: 1em;
     margin-left: 1em;
   }
   collapse.mdm-panel-body collapsing.mdm-panel-body {
       margin: 1em;
   }

Common reusable function:

 function toggleCollapser(e) {
     $(e.target)
         .prev('.panel-heading')
         .find('.mdm-panel-collapser')
         .toggleClass('glyphicon-chevron-down glyphicon-chevron-up');
 
   // Prevent bubble up to any parent collapsers.
   // This allows nested collapsers, whoop.
   e.stopPropagation();
 }

D3

ALWAYS initialize incoming data

Hard-earned data-import lessons:

tsv() will do complete date formatting, so when you remove it to use JSON directly, you HAVE TO convert JSON timestamps of ANY kind to full Javascript date objects:

 var data = [{"date":"2017-04-01T04:00:00.000Z",...
 // MDM WE MUST MASSAGE DATA HERE
 // JSON VALUES ARE ALWAYS STRINGS, we need to change to Javascript DATE!
 // Incoming datasets need a bit of massaging.
 // We do that in a function so we can reuse it on incoming dataset updates.
 function initializeDataset(dataset) {
     // TIME ON X
     // Convert date strings to actual date values.
     // MDM MAKE SURE this matches the incoming format.
     // Adding date so we can run the chart across days without trouble.
     // var parseDate = d3.time.format("%H:%M:%S %m-%d-%Y").parse;
     // var parseDate = d3.timeParse("%Y %b %d");
     var parseDate = d3.utcParse("%Y-%m-%dT%H:%M:%S.%LZ");
     dataset.forEach(function(d) {
         // there is NO SKIPING THIS STEP, you have to get valid Javascript date objects out of JSON strings
         d.date = parseDate(d.date);
         // we WOULD have to divide all data by zero,
         // but we already grabbed post-data that was already converted
         // This WORKS but makes data / 10000 (very small numbers)
         //for (var i = 1, n = dataset.columns.length; i < n; ++i) d[dataset.columns[i]] = d[dataset.columns[i]] / 100;
     });
 }
 initializeDataset(data);

tsv() will create an ARRAY but it also jams in a columns PROPERY; it takes two steps to duplicate that:

  var data = [
    {"date":"2015-06-15T04:00:00.000Z","Google Chrome":0.48090000000000005,...},
    {"date":"2015-06-22T04:00:00.000Z","Google Chrome":0.48979999999999996,...),
 ];
 data.columns = ["date","Google Chrome","Internet Explorer",...  ];

ALWAYS set range and domain properly

You have to know your display size (range) and the min and max of your data (domain), on each axis. From Mike's docs:

D3’s scales specify a mapping from data space (domain) to display space (range).

       D3’s scales can also be used to interpolate many other 
       types of display-space values, such as paths, color spaces 
       and geometric transforms.
       
         var x = d3.scale.linear()
             .domain([0, d3.max(data)])
             .range([0, 420]);
 
       Although x here looks like an object, it is also a function 
       that returns the scaled display value in the range 
       for a given data value in the domain. 
       For example, an input value of 4 returns 40, and an input value of 16 
       returns 160. To use the new scale, simply replace the 
       hard-coded multiplication by calling the scale function:
       
       d3.select(".chart")
         .selectAll("div")
           .data(data)
         .enter().append("div")
           .style("width", function(d) { return x(d) + "px"; })
           .text(function(d) { return d; });

Watch out for Mike's examples where he (trickily) doesn't bother to set a domain because his data is in the [0..1] set, and that's the default domain, apparently.

Jquery

Vega-lite