node.js调用一些使用OOP方法的方法

Question

我需要使用OOP方法调用一些方法，例如， this.method（）但我得到一些错误，这是我的BingoCard.js帮助请。

var _  = require('underscore'); 

// ------------------------------------ --------- 
// Constructor 
// --------------------------------------------- 
function BingoCard() { 
    if(false === (this instanceof BingoCard)) { 
     return new BingoCard(); 
    } 
    this.firstRowSchema = []; 
    this.secondRowSchema = []; 
    this.thirdRowSchema = []; 
    this.firstRow = []; 
    this.secondRow = []; 
    this.thirdRow = []; 
    this.patterns = [ 
    { 
     "1" : ['x','0','x','0','x','0','x','x','0'], 
     "2" : ['0','x','0','x','0','x','0','x','x'], 
     "3" : ['x','0','x','0','x','0','x','0','x'] 
    }, 
    { 
     "1" : ['x','x','0','x','0','x','0','x','0'], 
     "2" : ['0','x','x','0','x','0','x','0','x'], 
     "3" : ['x','0','x','x','0','x','0','x','0'] 
    } 
    ]; 
    this.columns = { 
         "1": [1,2,3,4,5,6,7,8,9], 
         "2": [10,11,12,13,14,15,16,17,18,19], 
         "3": [20,21,22,23,24,25,26,27,28,29], 
         "4": [30,31,32,33,34,35,36,37,38,39], 
         "5": [40,41,42,43,44,45,46,47,48,49], 
         "6": [50,51,52,53,54,55,56,57,58,59], 
         "7": [60,61,62,63,64,65,66,67,68,69], 
         "8": [70,71,72,73,74,75,76,77,78,79], 
         "9": [80,81,82,83,84,85,86,87,88,89,90] 
        }; 

    // Use Underscore to bind all of our methods 
    // to the proper context 
    _.bindAll(this); 
} 
// --------------------------------------------- 
// Methods 
// --------------------------------------------- 
BingoCard.prototype = { 
    resetSchemas: function() { 
     this.firstRowSchema = []; 
     this.secondRowSchema = []; 
     this.thirdRowSchema = []; 
    }, 
    generateRows: function() { 
     this.cardID = _.random(8888, 999999999); // generate a Card ID. 
     var pattern = _.shuffle(this.patterns); 
     this.firstRow = pattern[0][1]; 
     this.secondRow = pattern[0][2]; 
     this.thirdRow = pattern[0][3]; 
    }, 
    createColNumber: function (col,equalNumbers) { 
     console.log(this.patterns); 
     var colNumber = this.getColNumber(col); 
     if(typeof equalNumbers !== 'undefined' && equalNumbers.length > 0){ 
       equalNumbers.forEach(function(val,key){ 
       while(colNumber == val){ 
        colNumber = this.getColNumber(col); 
       } 
      }); 
     } 
     return colNumber; 
    }, 
    getColNumber: function() { 
     var items = _.shuffle(this.columns[col]); 
     return items[0]; 
    }, 
    generateFirstRow: function() { 
     var col = 0; 
     this.firstRow.forEach(function(val,key){ 
      col++; 
      if(val == 'x'){ 
       this.firstRowSchema[key] = this.createColNumber(col); 
      } else { 
       this.firstRowSchema[key] = 0; 
      } 
     }); 
     return this.firstRowSchema; 
    } 
}; 

// --------------------------------------------- 
// Export 
// --------------------------------------------- 
module.exports = BingoCard; 

我在app.js中调用了bingocard类，这是我的app.js内容。

var BingoCard  = require('./bingocard'); 
var bingocard  = new BingoCard(); 

bingocard.generateRows(); 
console.log(bingocard.generateFirstRow()); 

当从控制台运行“节点应用”我得到这个错误：

TypeError: Object #<Object> has no method 'createColNumber' 
    at /var/www/bingo/bingocard.js:10:48 

但定义createColNumber方法.. :(

Answer 1

在第四行下面的代码，这是不是指的原型。this指向别的东西。

this.firstRow.forEach(function(val,key){ 
      col++; 
      if(val == 'x'){ 
       this.firstRowSchema[key] = this.createColNumber(col); 
      } else { 
       this.firstRowSchema[key] = 0; 
      } 
     }); 

你可以用self来切换出this来解决这个问题。并在方法定义的开始处将其分配给self。像这样：

generateFirstRow: function() { 
     var col = 0, 
      self = this; 
     this.firstRow.forEach(function(val,key){ 
      col++; 
      if(val == 'x'){ 
       self.firstRowSchema[key] = self.createColNumber(col); 
      } else { 
       self.firstRowSchema[key] = 0; 
      } 
     }); 
     return this.firstRowSchema; 
    }