slevithan

// Simulating infinite-length leading lookbehind in JavaScript. Uses XRegExp.
// Captures within lookbehind are not included in match results. Lazy
// repetition in lookbehind may lead to unexpected results.

(function (XRegExp) {

    function prepareLb(lb) {
        // Allow mode modifier before lookbehind
        var parts = /^((?:\(\?[\w$]+\))?)\(\?<([=!])([\s\S]*)\)$/.exec(lb);
        return {

fengdi

function getValueByPath(obj, path){
  	(path+"").replace(/[^.:]+/g,function(n){
		obj = (obj!=void 0 && (typeof obj=="object" || typeof obj=="function") && n in obj) ? obj[n] : void 0;
	});
	return obj;
}

// getValueByPath({a:[{c:"r"}]}, "a.0.c"); // r

fengdi

function setValueByPath(obj, path, value){
	var temp, k, re = obj;
	if(!obj || (typeof obj!="object" && typeof obj!="function"))
		return obj;
	(path+"").replace(/([^.:]+)([.:])?/g, function(m, n, sign){
		temp = obj;
		k = n;
		obj = obj[n] = (obj!=void 0 && (typeof obj=="object" || typeof obj=="function") && n in obj) ? obj[n] : sign ==":" ?  [] : {};
	});
	if(k && temp){