javascript rails 编程

 function map(ls,func){
       var d=[]; 
       for(var i=0;i<ls.length;i++){
               d.push(func.call(this,ls[i]))
       }
       return d;
 }
 map([1,2,3],function(n){return n+1})
[2, 3, 4]

 function select(ls,func){
       var d=[]; 
       for(var i=0;i<ls.length;i++){
               if(func.call(this,ls[i]))
               d.push(ls[i])
       }
       return d;
 }
 select([1,2,3],function(n){return n%2==0;})
2

function reject(ls,func){    
      var d=[];     
      for(var i=0;i<ls.length;i++){    
              if(!func.call(this,ls[i])){d.push(ls[i])}    
      }    
      return d; 
}   
reject([1,2,3,4,5,6],function(n){ return n%2==0})  

function any(ls,func){  
      for(var i=0;i<ls.length;i++){  
              if(func.call(this,ls[i]))  
                   return true  
      }  
      return false;  
} 
function truth(n){ if(n){return true}else{return false}}

any([1,0,1],truth)
true

function all(ls,func){       
      for(var i=0;i<ls.length;i++){    
              if(!func.call(this,ls[i]))    
                   return false;
      }    
      return true;
}   
function truth(n){ if(n){return true}else{return false}}  
all([1,0,1],truth)  

function max(ls,func){    
    var d = ls.sort(func);console.log(d); return d[0];
}   
max([1,2,3,4,5,6],function(s1,s2){ if(s1.age <= s2.age){return -1}else{return 1} }) 

function min(ls,func){    
    var d = ls.sort(func);console.log(d); return d[0];
}   
min([1,2,3,4,5,6],function(s1,s2){ if(s1.age > s2.age){return -1}else{return 1} }) 

function uniq(ls){    
    var d =[];var r=[]; 
    for(var i=0;i<ls.length;i++){ d[ls[i]] = ls[i];} 
    for(var field in d){r.push(d[field])};
    return r;
}
uniq([1,2,3,4,5,6,1]) 

[1, 2, 3, 4, 5, 6]

function range(start,end,step)
             { 
               if(arguments.length==1){end=start;start=1;step=1;} 
               if(!step){step=1}; 
               var r=[]; 
               for(var i=start;i<=end;i=i+step){r.push(i)} return r;
             }
range(10)
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
range(1,10)
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
range(2,10)
[2, 3, 4, 5, 6, 7, 8, 9, 10]

function fib(n){ return n<2 ? n : arguments.callee(n-1) + arguments.callee(n-2) }

function delay(func,time,args){console.log(args);
setTimeout(function(args){ 
               return ( function(){func.apply(this,args)} )()}
           ,time)};
delay(function(n){alert("yes "+n)},1000,10);

bind = function(func, obj) {
    return function() {
      return func.apply(obj, arguments);
    };
  };

当然之前写的rails 风格的代码以及有人实现，名叫 Underscore.js，
感兴趣的人可以看看
http://documentcloud.github.com/underscore

其中有几个经典的用法

var fibonacci = function(n) {
  return n < 2 ? n : fibonacci(n - 1) + fibonacci(n - 2);
};
var fastFibonacci = _.memoize(fibonacci);


_.mixin({
  capitalize : function(string) {
    return string.charAt(0).toUpperCase() + string.substring(1).toLowerCase();
  }
});
_("fabio").capitalize();
=> "Fabio"


var compiled = _.template("hello: <%= name %>");
compiled({name : 'moe'});
=> "hello: moe"

var list = "<% _.each(people, function(name) { %> <li><%= name %></li> <% }); %>";
_.template(list, {people : ['moe', 'curly', 'larry']});
=> "<li>moe</li><li>curly</li><li>larry</li>"

评论

1 楼 edisonlz 2011-05-06  

为啥没人回复啊，大家对这种写法很陌生吗?