JavaScript策略模式详解：定义、应用与参数配置优化

策略模式应用：年终奖计算

 //封装了所有算法的策略对象
var strategies = {
  'S': function(salary){
    return salary*4;
  },
  'A': function(salary){
    return salary*3;
  },
  'B': function(salary){
    return salary*2;
  },
  'C': function(salary){
    return salary*1;
  }
} //定义自动选择算法的方法
var calculateBonus = function(level,salary){
  return strategies[level](salary);
}
//使用
calculateBonus('S',9000); //36000
calculateBonus('B',5000); //10000 

策略模式应用：表单验证实现

 //定义验证算法的策略对象
var strategies = function(){
  isEmpty:function(value,errorMsg){
    if(value = ''){
      return errorMsg;
    }
  }
  outRangle:function(value,min,max,errorMsg){
    if(value.length > max || value.length < min){
      return errorMsg;
    }
  }
  isSame:function(oldValue,newValue,errorMsg){
    if(newValue !== oldValue){
      return errorMsg;
    }
  }
  isMobile:function(value,errorMsg){
    if(!/(^1[3|5|8][0-9]{9}$)/.test(value)){
      return errorMsg;
    }
  }
  ......
} 

 //定义Validator
var Validator = function(){
  this.cache = [];
}
Validator.prototype.add = function(elem,rules){
  var self = this;
  for(var i = 0, rule; rule = rules[i++]){
    (function(rule){
      var strategyAry = rule.strategy.split(':');
      var errorMsg = rule.errorMsg;
      self.cache.push(function(){
        var strategy = strategyAry.shift();
        strategyAry.unshift(elem.value);
        strategyAry.push(errorMsg);
        return strategies[strategy].apply(elem,strategyAry);
      })
    })(rule)
  }
}
Validator.prototype.start = function(){
  for(var i = 0, func; func = this.cache[i++]){
    var errorMsg = func();
    if(errorMsg){
      return errorMsg;
    }
  }
} 

var validator = new Validator();
validator.add(elem.userName,[
  {strategy:'isEmpty', errorMsg:'用户名不能为空'},
  {strategy:'outRangle:6:12', errorMsg:'用户名长度为6-12位'}
]);
......
var errorMsg = validator.start();
...... 

参数配置对象优化技巧

 var prop = {
  a:55,
  b:'ss',
  c:function(){...}
  d:{x:1,y:2}
  ...
}
foo(prop);