json对象转字符串如何实现_javascript技巧

function test_toStringify(){
var result = {
"JSON.stringify(undefined)": JSON.stringify(undefined),
"JSON.stringify(null)": JSON.stringify(null),
"JSON.stringify(123)": JSON.stringify(123),
"JSON.stringify(true)": JSON.stringify(true),
"JSON.stringify('')": JSON.stringify(''),
"JSON.stringify('abc')": JSON.stringify('abc'),
"JSON.stringify(null)": JSON.stringify(null),
"JSON.stringify([1,2,3])": JSON.stringify([1,2,3]),
"JSON.stringify([undefined, undefined])": JSON.stringify([undefined, undefined]),
"JSON.stringify({name:'chyingp', age:24, u:undefined})": JSON.stringify({name:'chyingp', age:24, u:undefined})
};
var str = '';
for(var key in result){
if(typeof result[key] === 'string'){
str += key + " : '" + result[key] + "'\n";
}else{
str += key + " : " + result[key] + "\n";
}
}
console.log(str);
}
test_toStringify();

JSON.stringify(undefined) : undefined
JSON.stringify(null) : 'null'
JSON.stringify(123) : '123'
JSON.stringify(true) : 'true'
JSON.stringify('') : '""'
JSON.stringify('abc') : '"abc"'
JSON.stringify([1,2,3]) : '[1,2,3]'
JSON.stringify([undefined, undefined]) : '[null,null]'
JSON.stringify({name:'chyingp', age:24, u:undefined}) : '{"name":"chyingp","age":24}'

function is_number(obj){ return Object.prototype.toString.call(obj)==='[object Number]'; }
function is_boolean(obj){ return Object.prototype.toString.call(obj)==='[object Boolean]'; }
function is_string(obj){ return Object.prototype.toString.call(obj)==='[object String]'; }
function is_null(obj){ return Object.prototype.toString.call(obj)==='[object Null]'; }
function is_undefined(obj){ return Object.prototype.toString.call(obj)==='[object Undefined]'; }
function is_object(obj){ return Object.prototype.toString.call(obj)==='[object Object]'; }
function is_array(obj){ return Object.prototype.toString.call(obj)==='[object Array]'; }
function is_function(obj){ return Object.prototype.toString.call(obj)==='[object Function]'; }
function quote(str){ return '"' + str + '"'; }
var basic_map = {
'[object Undefined]': true,
'[object Number]': true,
'[object Null]': true,
'[object Boolean]': true
}
function basic_type(obj){ return basic_map[ Object.prototype.toString.call(obj) ]; }
JSON = window.JSON || {};
//其实就是JSON.stringify
JSON.toStr = function(obj){
if(is_string(obj) || is_null(obj) || is_number(obj) || is_boolean(obj)) return quote(obj);
if(is_undefined(obj)) return obj;
if(is_array(obj)){
var left = "[",
middle = [],
right = "]",
value;
var callee = arguments.callee;
for(var i=0,len=obj.length; ivar value = obj[i];
if( typeof value === 'undefined' ){
middle.push(null+'');
}else{
if( basic_type(value) ){
middle.push( value )
}else{
middle.push( callee(obj[i]) )
}
}
}
return left+ middle.join(",") +right;
}
if(is_object(obj)){
var left = "{",
middle = [],
right = "}",
value ;
var callee = arguments.callee;
for(var key in obj){
var value = obj[key];
if(typeof obj[key] === 'undefined') continue;
if( basic_type(value) ){
middle.push( quote(key) + ':'+ value );
}else{
middle.push( quote(key) + ':'+ callee(value) );
}
}
return left + middle.join(', ') + right;
}
};
!JSON.stringify && (JSON.stringify = JSON.toStr);