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Copy pathJSON_parser.js
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186 lines (170 loc) · 5.04 KB
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var parseBtn = document.querySelector('#btn')
var pText = document.querySelector('p')
parseBtn.addEventListener('click', function(){
var JsonString = document.querySelector('#JSON_area').value
pText.innerHTML = "The result is in Dev tools"
console.log(jsonpars(JsonString))
})
function jsonpars(jsonString) {
var theJson = '',
index = 0,
onOff = false
// clear blank
for (var i = 0; i < jsonString.length; i++) {
if (jsonString[i] == '"') {
onOff = onOff ? false : true
}
if (!onOff &&
(jsonString[i] == ' ' ||
jsonString[i] == '\n' ||
jsonString[i] == '\r' ||
jsonString[i] == '\t')) {
continue
}
theJson = theJson + jsonString[i]
}
return parse()
/**
* 指针指向合适的位置时进行的解析函数，根据字符串不同的表现返回不同的值
* @param {string} jsonString 当前需要解析的字符串（可能是递归后的值）
* @param {number} index var indexChar[指针]
* @return {*} 解析后的值
*/
function parse() {
var indexChar = theJson[index]
if (indexChar == '{') {
return parseObject()
}
if (indexChar == '[') {
return parseArray()
}
if (indexChar == 't') {
return parseTrue()
}
if (indexChar == 'f') {
return parseFalse()
}
if (indexChar == 'n') {
return parseNull()
}
if (indexChar == '"') {
return parseString()
}
if (isDigit(indexChar)) {
return parseNumber()
}
}
/**
* parseNumber 解析值为数字的 value
* @return {number *}
*/
function parseNumber() {
for (var i = index + 1;; i++) {
if (!isDigit(theJson[i])) {
break
}
}
var num = theJson.slice(index, i)
index = i
return parseInt(num)
}
/**
* 判断一个字符能否转换为数字
* @param {string} char 传入的单个字符
* @return {Boolean} 如果能转换为数字，返回true
*/
function isDigit(char) {
if (!char) {
return false
}
var the0 = '0'.charCodeAt(0)
var the9 = '9'.charCodeAt(0)
var theChar = char.charCodeAt(0)
if (the0 <= theChar && theChar <= the9) {
return true
} else {
return false
}
}
/**
* parseString 解析值为字符串的value值
* @return {string} 返回作为值的字符串
*/
function parseString() {
var theEnd = theJson.indexOf('"', index + 1)
var theString = theJson.slice(index + 1, theEnd)
index = theEnd + 1
return theString
}
/**
* parseNull 解析 值为null的value值
* @return {string *} 返回null
*/
function parseNull() {
index += 4
return null
}
/**
* parseFalse 解析值为 false 的 value 值
* @return {boolean} 返回false
*/
function parseFalse() {
index += 5
return false
}
/**
* parseFalse 解析值为 true 的 value 值
* @return {boolean} 返回true
*/
function parseTrue() {
index += 4
return true
}
/**
* parseArray 递归解析数组
* @return {array} 返回一个数组
*/
function parseArray() {
var result = [],
product
index++
for (;;) {
product = parse()
result.push(product)
if (theJson[index] === ',') {
index++
continue
}
if (theJson[index] === ']') {
break
}
}
index++
return result
}
/**
* parseObject 递归解析对象
* @return {object} 返回对象
*/
function parseObject() {
var result = {},
key,
value
index++
for (;;) {
key = parseString()
index++
value = parse()
result[key] = value
if (theJson[index] === "}") {
break
}
if (theJson[index] === ",") {
index++
continue
}
}
index++
return result
}
}