gallery/number-format.js

   1 /*global Gallery,Dygraph,data */
   2 Gallery.register(
   3   'number-format',
   4   {
   5     name: 'Number formatting',
   6     setup: function(parent) {
   7       parent.innerHTML =
   8           "<p>The default formatting mimics printf with %.<i>p</i>g where <i>p</i> is" +
   9           "   the precision to use.  It turns out that JavaScript's toPrecision()" +
  10           "   method is almost but not exactly equal to %g; they differ for values" +
  11           "   with small absolute values (10^-1 to 10^-5 or so), with toPrecision()" +
  12           "   yielding strings that are longer than they should be (i.e. using fixed" +
  13           "   point where %g would use exponential).</p>" +
  14
  15           "<p>This test is intended to check that our formatting works properly for a" +
  16           "   variety of precisions.</p>" +
  17
  18           "<p>Precision to use (1 to 21):" +
  19           "  <input type='text' id='p_input' size='20'></p>" +
  20           "<p/>" +
  21           "<div id='content' style='font-family:Courier New,monospace'></div>";
  22     },
  23     run: function() {
  24       // Helper functions for generating an HTML table for holding the test
  25       // results.
  26       var createRow = function(columnType, columns) {
  27         var row = document.createElement('tr');
  28         for (var i = 0; i  < columns.length; i ++) {
  29           var th = document.createElement(columnType);
  30           var text = document.createTextNode(columns[i]);
  31           th.appendChild(text);
  32           row.appendChild(th);
  33         }
  34         return row;
  35       };
  36
  37       var createHeaderRow = function(columns) {
  38         return createRow('th', columns);
  39       };
  40
  41       var createDataRow = function(columns) {
  42         return createRow('td', columns);
  43       };
  44
  45       var createTable = function(headerColumns, dataColumnsList) {
  46         var table = document.createElement('table');
  47         table.appendChild(createHeaderRow(headerColumns));
  48         for (var i = 0; i < dataColumnsList.length; i++) {
  49           table.appendChild(createDataRow(dataColumnsList[i]));
  50         }
  51         return table;
  52       };
  53
  54       var updateTable = function() {
  55         var headers = ['Dygraph.floatFormat()', 'toPrecision()',
  56                        'Dygraph.floatFormat()', 'toPrecision()'];
  57         var numbers = [];
  58         var p = parseInt(document.getElementById('p_input').value, 10);
  59
  60         for (var i = -10; i <= 10; i++) {
  61           var n = Math.pow(10, i);
  62           numbers.push([Dygraph.floatFormat(n, p),
  63                         n.toPrecision(p),
  64                         Dygraph.floatFormat(Math.PI * n, p),
  65                         (Math.PI * n).toPrecision(p)]);
  66         }
  67
  68         // Check exact values of 0.
  69         numbers.push([Dygraph.floatFormat(0.0, p),
  70                       (0.0).toPrecision(p)]);
  71
  72         var elem = document.getElementById('content');
  73         elem.innerHTML = '';
  74         elem.appendChild(createTable(headers, numbers));
  75       };
  76
  77       document.getElementById('p_input').value = '4';
  78       document.getElementById('p_input').onchange = updateTable;
  79       updateTable();
  80     }
  81   });