js 常用基本知识

Object.isObject = function(obj){
    return obj != null && typeof obj === 'object' && Array.isArray(obj) === false;  
}

Number.isNumber = function(num){
    return typeof num ==='number' && isFinite(num);
}

Object.find = function(obj = {}, path = ''){
	path = path.split('.');
	let idx = 0, len = path.length;
	while(obj != null && idx < len){ obj = obj[path[idx++]] }
	return (idx && idx == len) ? obj : undefined;
}

Object.only = function(obj, keys){
  obj = obj || {};
  if ('string' == typeof keys) keys = keys.split(/ +/);
  return keys.reduce(function(ret, key){
    if (null == obj[key]) return ret;
    ret[key] = obj[key];
    return ret;
  }, {});
};

/**
* 
*/
Object.only = function(obj, keys){
  obj = obj || {};
  if ('string' == typeof keys) keys = keys.split(/ +/);
  return keys.reduce(function(ret, key){
    if (null == obj[key]) return ret;
    ret[key] = obj[key];
    return ret;
  }, {});
};