前言
这是一道笔试题，要求模拟实现JSON.stringiry 的格式化输出,按照层级缩进，输出易读格式，即完成以下方法
JSON.stringify(jsObj, null, 4); // 缩进4个空格
如输入：
{a:1,b:[{bb:1},{bb:2}],c:"cc"}
字符打印结果：
{
"a": 1,
"b": [
{
"bb": 1
},
{
"bb": 2
}
],
"c": "cc"
}
具体实现：
function isArray(obj) {
if (Array.isArray) {
return Array.isArray(obj);
} else {
return Object.prototype.toString.call(obj) == "[object Array]";
}
}
function isObject(obj) {
return Object.prototype.toString.call(obj) == "[object Object]";
}
function isString(obj) {
return typeof obj == "string";
}
function isNull(obj) {
return typeof obj == "null";
}
function processValue(value) {
if (!isString(value)) {
if (!isNull(value)) {
return value.toString(); // 针对Number和Boolean
} else {
return null;
}
} else {
return '"' + value.toString() + '"';
}
}
function jsonStringify(value, indent) {
var indent = indent || "";
var ret = indent + "{\n";
indent += " ";
var keys = Object.keys(value);
for (var i = 0; i < keys.length; i++) {
var key = keys[i];
var v = value[key];
ret += (indent + processValue(key) + ":");
if (!isArray(v) || isObject(v)) {
ret += processValue(v);
} else {
var ind = indent + " ";
for (var k = 0; k < key.length; k++) {
ind += " ";
}
if (isArray(v)) {
ret += "[\n";
for (var j = 0; j < v.length; j++) {
ret += jsonStringify(v[j], ind);
if (j == v.length - 1) {
ret += "\n";
} else {
ret += ",\n";
}
}
ret += indent + ']';
} else if (isObject(v)) {
ret += jsonStringify(v, ind);
}
}
if (i == keys.length - 1) {
ret += "\n"
} else {
ret += ",\n"
}
}
ret += indent.slice(4) + "}";
return ret;
}
var result = jsonStringify({
a: 1,
b: [{
bb: 1
}, {
bb: 2
}],
c: "cc"
});
console.log(result);