ui/webui/resources/js/load_time_data.js

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 /**
   6  * @fileoverview This file defines a singleton which provides access to all data
   7  * that is available as soon as the page's resources are loaded (before DOM
   8  * content has finished loading). This data includes both localized strings and
   9  * any data that is important to have ready from a very early stage (e.g. things
  10  * that must be displayed right away).
  11  */
  12
  13 var loadTimeData;
  14
  15 (function() {
  16   'use strict';
  17
  18   function LoadTimeData() {
  19   }
  20
  21   LoadTimeData.prototype = {
  22     /**
  23      * Sets the backing object.
  24      * @param {Object} value The de-serialized page data.
  25      */
  26     set data(value) {
  27       expect(!this.data_, 'Re-setting data.');
  28       this.data_ = value;
  29     },
  30
  31     /**
  32      * @return {boolean} True if |id| is a key in the dictionary.
  33      */
  34     valueExists: function(id) {
  35       return id in this.data_;
  36     },
  37
  38     /**
  39      * Fetches a value, expecting that it exists.
  40      * @param {string} id The key that identifies the desired value.
  41      * @return {*} The corresponding value.
  42      */
  43     getValue: function(id) {
  44       expect(this.data_, 'No data. Did you remember to include strings.js?');
  45       var value = this.data_[id];
  46       expect(typeof value != 'undefined', 'Could not find value for ' + id);
  47       return value;
  48     },
  49
  50     /**
  51      * As above, but also makes sure that the value is a string.
  52      * @param {string} id The key that identifies the desired string.
  53      * @return {string} The corresponding string value.
  54      */
  55     getString: function(id) {
  56       var value = this.getValue(id);
  57       expectIsType(id, value, 'string');
  58       return value;
  59     },
  60
  61     /**
  62      * Returns a formatted localized string where $1 to $9 are replaced by the
  63      * second to the tenth argument.
  64      * @param {string} id The ID of the string we want.
  65      * @param {...string} The extra values to include in the formatted output.
  66      * @return {string} The formatted string.
  67      */
  68     getStringF: function(id) {
  69       var value = this.getString(id);
  70       if (!value)
  71         return;
  72
  73       var varArgs = arguments;
  74       return value.replace(/\$[$1-9]/g, function(m) {
  75         return m == '$$' ? '$' : varArgs[m[1]];
  76       });
  77     },
  78
  79     /**
  80      * As above, but also makes sure that the value is a boolean.
  81      * @param {string} id The key that identifies the desired boolean.
  82      * @return {boolean} The corresponding boolean value.
  83      */
  84     getBoolean: function(id) {
  85       var value = this.getValue(id);
  86       expectIsType(id, value, 'boolean');
  87       return value;
  88     },
  89
  90     /**
  91      * As above, but also makes sure that the value is an integer.
  92      * @param {string} id The key that identifies the desired number.
  93      * @return {number} The corresponding number value.
  94      */
  95     getInteger: function(id) {
  96       var value = this.getValue(id);
  97       expectIsType(id, value, 'number');
  98       expect(value == Math.floor(value), 'Number isn\'t integer: ' + value);
  99       return value;
 100     },
 101
 102     /**
 103      * Override values in loadTimeData with the values found in |replacements|.
 104      * @param {Object} replacements The dictionary object of keys to replace.
 105      */
 106     overrideValues: function(replacements) {
 107       expect(typeof replacements == 'object',
 108              'Replacements must be a dictionary object.');
 109       for (var key in replacements) {
 110         this.data_[key] = replacements[key];
 111       }
 112     }
 113   };
 114
 115   /**
 116    * Checks condition, displays error message if expectation fails.
 117    * @param {*} condition The condition to check for truthiness.
 118    * @param {string} message The message to display if the check fails.
 119    */
 120   function expect(condition, message) {
 121     if (!condition)
 122       console.error(message);
 123   }
 124
 125   /**
 126    * Checks that the given value has the given type.
 127    * @param {string} id The id of the value (only used for error message).
 128    * @param {*} value The value to check the type on.
 129    * @param {string} type The type we expect |value| to be.
 130    */
 131   function expectIsType(id, value, type) {
 132     expect(typeof value == type, '[' + value + '] (' + id +
 133                                  ') is not a ' + type);
 134   }
 135
 136   expect(!loadTimeData, 'should only include this file once');
 137   loadTimeData = new LoadTimeData;
 138 })();