2.07 - an example illustrating the use of the interface class.js

JS设计模式源代码

// ResultFormatter class, before we implement interface checking.

var ResultFormatter = function(resultsObject) {
  if(!(resultsObject instanceOf TestResult)) {
    throw new Error('ResultsFormatter: constructor requires an instance '
      + 'of TestResult as an argument.');
  }
  this.resultsObject = resultsObject;
};

ResultFormatter.prototype.renderResults = function() {
  var dateOfTest = this.resultsObject.getDate();
  var resultsArray = this.resultsObject.getResults();
  
  var resultsContainer = document.createElement('div');

  var resultsHeader = document.createElement('h3');
  resultsHeader.innerHTML = 'Test Results from ' + dateOfTest.toUTCString();
  resultsContainer.appendChild(resultsHeader);
  
  var resultsList = document.createElement('ul');
  resultsContainer.appendChild(resultsList);
  
  for(var i = 0, len = resultsArray.length; i < len; i++) {
    var listItem = document.createElement('li');
    listItem.innerHTML = resultsArray[i];
    resultsList.appendChild(listItem);
  }
  
  return resultsContainer;
};


// ResultSet Interface.

var ResultSet = new Interface('ResultSet', ['getDate', 'getResults']);

// ResultFormatter class, after adding Interface checking.

var ResultFormatter = function(resultsObject) {
  Interface.ensureImplements(resultsObject, ResultSet);
  this.resultsObject = resultsObject;
};

ResultFormatter.prototype.renderResults = function() {
  ...
};