jquery中extend, $.extend源码分析

 
o.extend = o.fn.extend = function() {
        var J = arguments[0] || {},
        H = 1,
        I = arguments.length,
        E = false,
        G;
        if (typeof J === "boolean") {
            E = J;
            J = arguments[1] || {};
            H = 2
        }
        if (typeof J !== "object" && !o.isFunction(J)) {
            J = {}
        }
        if (I == H) {
            J = this; --H
        }
        for (; H < I; H++) {
            if ((G = arguments[H]) != null) {
                for (var F in G) {
                    var K = J[F],
                    L = G[F];
                    if (J === L) {
                        continue
                    }
                    if (E && L && typeof L === "object" && !L.nodeType) {
                        J[F] = o.extend(E, K || (L.length != null ? [] : {}), L)
                    } else {
                        if (L !== g) {
                            J[F] = L
                        }
                    }
                }
            }
        }
        return J
    };

 
(function(){
    var s={};
    s.extend=function(){
        var a=arguments[0]||{},
            e=false, //是否是深拷贝
            h=0,  //参数个数
            j=arguments[1],
            n=arguments.length,g;
            if(typeof arguments[0]==='boolean'){
                e=arguments[0];
                h=1;
            };
            for(;h                 g=arguments[h];
                if(typeof g !=null){
                    for(var t in g){
                        if(e && g[t] && typeof g[t]=='object' && !g[t].nodeType){//深拷贝
                            o.extend(e,(j||{}),g[t]);
                        }else{
                            if(g[t]!=undefined){
                                j[t]=g[t]; //拷贝
                            }
                        }
                    }
                }
            }
            return j;
    };
    var c=s.extend({a:10},{name:'siren',t:{age:20,sex:1}})
    console.log(c)
})()