有没有办法遍历JavaScript JSON对象而无需递归？
例如在关联数组中查找节点的邻居？
答案 0 :(得分：1)
有趣的问题，做了一些可以解决您问题的方法-JSON迭代器IIFE。 抱歉，忘记包含演示部件，因此现在作为摘要：
'use strict';
function test(json) {
var it = new JIterator(json);
var i = 0;
console.log("DepthFirst traverse:");
do {
console.log(i++ + '\t' + it.Level + '\t' + it.Path().join('.') + '\t' + it.KeyDots(), (it.Value() instanceof Object) ? (it.Value() instanceof Array ? "[]" : "{}") : it.Value());
} while (it.DepthFirst());
}
var JNode = (function (jsNode) {
function JNode(_parent, _pred, _key, _value) {
this.parent = _parent;
this.pred = _pred;
this.node = null;
this.next = null;
this.key = _key;
this.value = _value;
}
return JNode;
})();
var JIterator = (function (json) {
var root, current, maxLevel = -1;
function JIterator(json, parent) {
if (parent === undefined) parent = null;
var pred = null, localCurrent;
for (var child in json) {
var obj = json[child] instanceof Object;
if(json instanceof Array) child = parseInt(child); // non-associative array
if (!root) root = localCurrent = new JNode(parent, null, child, json[child]);
else {
localCurrent = new JNode(parent, pred, child, obj ? ((json[child] instanceof Array) ? [] : {}) : json[child]);
}
if (pred) pred.next = localCurrent;
if (parent && parent.node == null) parent.node = localCurrent;
pred = localCurrent;
if (obj) {
var memPred = pred;
JIterator(json[child], pred);
pred = memPred;
}
}
if (this) {
current = root;
this.Level = 0;
}
}
JIterator.prototype.Current = function () { return current; }
JIterator.prototype.Parent = function () {
var retVal = current.parent;
if (retVal == null) return false;
this.Level--;
return current = retVal;
}
JIterator.prototype.Pred = function () {
var retVal = current.pred;
if (retVal == null) return false;
return current = retVal;
}
JIterator.prototype.Node = function () {
var retVal = current.node;
if (retVal == null) return false;
this.Level++;
return current = retVal;
}
JIterator.prototype.Next = function () {
var retVal = current.next;
if (retVal == null) return false;
return current = retVal;
}
JIterator.prototype.Key = function () { return current.key; }
JIterator.prototype.KeyDots = function () { return (typeof(current.key) == "number")?"":(current.key+':'); }
JIterator.prototype.Value = function () { return current.value; }
JIterator.prototype.Reset = function () {
current = root;
this.Level = 0;
}
JIterator.prototype.RawPath = function () {
var steps = [], level = current;
do {
if (level != null && level.value instanceof Object) {
steps.push(level.key + (level.value instanceof Array ? "[]" : "{}"));
} else {
if (level != null) steps.push(level.key);
else break;
}
level = level.parent;
} while (level != null);
var retVal = "";
retVal = steps.reverse();
return retVal;
}
JIterator.prototype.Path = function () {
var steps = [], level = current;
do {
if (level != null && level.value instanceof Object) {
var size = 0;
var items = level.node;
if(typeof(level.key) == "number") steps.push('[' + level.key + ']');
else {
while(items) {
size++;
items = items.next;
}
var type = (level.value instanceof Array ? "[]" : "{}");
var prev = steps[steps.length-1];
if(prev && prev[0] == '[') {
var last = prev.length-1;
if(prev[last] == ']') {
last--;
if(!isNaN(prev.substr(1, last))) {
steps.pop();
size += '.' + prev.substr(1, last);
}
}
}
steps.push(level.key + type[0] + size + type[1]);
}
} else {
if (level != null) {
if(typeof(level.key) == "number") steps.push('[' + level.key + ']');
else steps.push(level.key);
}
else break;
}
level = level.parent;
} while (level != null);
var retVal = "";
retVal = steps.reverse();
return retVal;
}
JIterator.prototype.DepthFirst = function () {
if (current == null) return 0; // exit sign
if (current.node != null) {
current = current.node;
this.Level++;
if (maxLevel < this.Level) maxLevel = this.Level;
return 1; // moved down
} else if (current.next != null) {
current = current.next;
return 2; // moved right
} else {
while (current != null) {
if (current.next != null) {
current = current.next;
return 3; // returned up & moved next
}
this.Level--;
current = current.parent;
}
}
return 0; // exit sign
}
JIterator.prototype.BreadthFirst = function () {
if (current == null) return 0; // exit sign
if (current.next) {
current = current.next;
return 1; // moved right
} else if (current.parent) {
var level = this.Level, point = current;
while (this.DepthFirst() && level != this.Level);
if (current) return 2; // returned up & moved next
do {
this.Reset();
level++;
while (this.DepthFirst() && level != this.Level);
if (current) return 3; // returned up & moved next
} while (maxLevel >= level);
return current != null ? 3 : 0;
} else if (current.node) {
current = current.node;
return 3;
} else if (current.pred) {
while (current.pred) current = current.pred;
while (current && !current.node) current = current.next;
if (!current) return null;
else return this.DepthFirst();
}
}
return JIterator;
})();
// Demo data
var demoJSON = {
"glossary": {
"title": "example glossary",
"GlossDiv": {
"title": "S",
"GlossList": {
"GlossEntry": {
"ID": "SGML",
"SortAs": "SGML",
"GlossTerm": "Standard Generalized Markup Language",
"Acronym": "SGML",
"Abbrev": "ISO 8879:1986",
"GlossDef": {
"para": "A meta-markup language, used to create markup languages such as DocBook.",
"GlossSeeAlso": [
"GML",
"XML"
]
},
"GlossSee": "markup"
}
}
}
}
}
test(demoJSON);