javascript 精粹笔记

//为构造函数原型添加方法
Function.method=function(name,func){

this.prototype.name=func;
}

Number.method("integer",function(){

return Math[this < 0 ? 'ceil':'floor'](this);
});
(-10/3).integer();//-3

String.method("trim",function(){
return this.replace(/^\s+|\s+$/g,'');
})
" neat ".trim();//neat
//闭包
var quo = function(status){

return{

get_status:function(){

return status;

}

}
}
var myQuo = new quo("amazed");
myQuo.get_status();//amazed

//闭包经典例子片段
for(var i=0;i<lis.length;i++){

lis.onclick=function(i){

return function(){

alert(i);

};

}(i);
}

//套用
Function.method("curry",function(){

var slice=Array.prototype.slice,

args = slice.apply(arguments),

that = this;

return function(){

return that.apply(null,args.contact(arguments));

}
})

//记忆 递归
var memoization = function(memo,usefn){//抽象化
var fn = function(n){
var result = memo[n];
if(typeof result!=='number'){
result=usefn(fn,n);
memo[n]=result;
}
return result;
};
return fn;
};
var factorial= memoization([0,1],function(fn,n){//递归的形式
return fn(n-1)*n
});
factorial(5)//120