gallery/number-format.js

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