瞧一瞧看一看

var object={b:{c:4},d:[{e:5},{e:6}]}

parse(object,"b.c")==4  //true
parse(object,"d[0].c")==5  //true
parse(object,"d.0.c")==5  //true
parse(object,"d[1].c")==6  //true
parse(object,"d.1.c")==6  //true
parse(object,"f")==undefined  //true

大神给个优秀的解决方案
完成parse函数的内部代码

5 个解决方案

#1

var object={b:{c:4},d:[{e:5},{e:6}]}
function parse(obj,v) {
	try {
		var str = ("obj."+v).replace(/\.(\d+)/g,"[$1]");
		return eval(str);
	} catch(eo){
		return undefined;
	}
}
console.log(parse(object,"b.c")==4);
console.log(parse(object,"d[0].e")==5);
console.log(parse(object,"d.0.e")==5);
console.log(parse(object,"d[1].e")==6);
console.log(parse(object,"d.1.e")==6);
console.log(parse(object,"f")==undefined);

#2

引用 1 楼 jslang 的回复:

var object={b:{c:4},d:[{e:5},{e:6}]}
function parse(obj,v) {
	try {
		var str = ("obj."+v).replace(/\.(\d+)/g,"[$1]");
		return eval(str);
	} catch(eo){
		return undefined;
	}
}
console.log(parse(object,"b.c")==4);
console.log(parse(object,"d[0].e")==5);
console.log(parse(object,"d.0.e")==5);
console.log(parse(object,"d[1].e")==6);
console.log(parse(object,"d.1.e")==6);
console.log(parse(object,"f")==undefined);

正则有点陌生 
replace(/\.(\d+)/g,"[$1]")
是啥替换成啥

#3

引用 2 楼 u013116426 的回复:

Quote: 引用 1 楼 jslang 的回复:

var object={b:{c:4},d:[{e:5},{e:6}]}
function parse(obj,v) {
	try {
		var str = ("obj."+v).replace(/\.(\d+)/g,"[$1]");
		return eval(str);
	} catch(eo){
		return undefined;
	}
}
console.log(parse(object,"b.c")==4);
console.log(parse(object,"d[0].e")==5);
console.log(parse(object,"d.0.e")==5);
console.log(parse(object,"d[1].e")==6);
console.log(parse(object,"d.1.e")==6);
console.log(parse(object,"f")==undefined);

正则有点陌生 
replace(/\.(\d+)/g,"[$1]")
是啥替换成啥

d.0.e 数字属性这样是不合法的，要把 .0 替换成 [0]

#4

楼主这道题很有意思，有些像AST，我借鉴AST一丢丢思想，写了个解析函数：

function parse(object, sentence){
	var chars = sentence.split(''), 
		nodes = [], 
		i, len, tmp;

	// 解析语句
	for(i=0, len=chars.length, tmp=''; i<len; ++i){
		switch(chars[i]){
			case '.':
				if(tmp){
					nodes.push(tmp);
					tmp = '';
				}
				break;
			case '[':
				if(tmp){
					nodes.push(tmp);
					tmp = '';
				}
				for(++i; i<len; ++i){  // 寻找“]”
					if(chars[i] === ']'){
						nodes.push(tmp);
						tmp = '';
						break;
					}else{
						tmp += chars[i];
					}
				}
				if(i === len) throw 'syntax error';
				break;
			default:
				tmp += chars[i];
		}
	}
	nodes.push(tmp);

	// 获取数据
	for(i=0, len=nodes.length, tmp=object; i<len; ++i){
		tmp = tmp[ nodes[i] ];
	}
	return tmp;
}

测试：

var object={b:{c:4},d:[{e:5},{e:6}]}；
console.log(parse(object,"b.c")==4);
console.log(parse(object,"d[0].e")==5);
console.log(parse(object,"d.0.e")==5);
console.log(parse(object,"d[1].e")==6);
console.log(parse(object,"d.1.e")==6);
console.log(parse(object,"f")==undefined);

#5

或者不用eval

var object={b:{c:4},d:[{e:5},{e:6}]}
function parse(obj,v) {
	var arr = v.match(/[\w\$]+/g);
	while(typeof obj=="object" && arr.length>0) {
		obj = obj[arr.shift()];
	}
	return obj;
}
console.log(parse(object,"b.c")==4);
console.log(parse(object,"d[0].e")==5);
console.log(parse(object,"d.0.e")==5);
console.log(parse(object,"d[1].e")==6);
console.log(parse(object,"d.1.e")==6);
console.log(parse(object,"f")==undefined);