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Key extractor that supports nested objects, nested arrays, duplicate keys, and cycles, returning an array of the unique keys.
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// All of these should return the keys "a", "b", "c" | |
var inputs = [ | |
{a:1,b:2,c:3}, // Simple object | |
{a:{b:2,c:3}}, // Simple object with nesting | |
{a:{a:{b:2,c:3}}}, // Repeated key hiding nesting | |
{a:[{b:2,c:3}]}, // keys behind array | |
]; | |
inputs.push(inputs); // reference cycle and array at top | |
function getKeys(obj) { | |
var all = {}; | |
var seen = []; | |
checkValue(obj); | |
return Object.keys(all); | |
function checkValue(value) { | |
if (Array.isArray(value)) return checkArray(value); | |
if (value instanceof Object) return checkObject(value); | |
} | |
function checkArray(array) { | |
if (seen.indexOf(array) >= 0) return; | |
seen.push(array); | |
for (var i = 0, l = array.length; i < l; i++) { | |
checkValue(array[i]); | |
} | |
} | |
function checkObject(obj) { | |
if (seen.indexOf(obj) >= 0) return; | |
seen.push(obj); | |
var keys = Object.keys(obj); | |
for (var i = 0, l = keys.length; i < l; i++) { | |
var key = keys[i]; | |
all[key] = true; | |
checkValue(obj[key]); | |
} | |
} | |
} | |
var result = inputs.map(getKeys); | |
console.log(result); |
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// All of these should return the keys "a", "b", "c" | |
var inputs = [ | |
{a:1,b:2,c:3}, // Simple object | |
{a:{b:2,c:3}}, // Simple object with nesting | |
{a:{a:{b:2,c:3}}}, // Repeated key hiding nesting | |
{a:[{b:2,c:3}]}, // keys behind array | |
]; | |
inputs.push(inputs); // reference cycle and array at top | |
function getKeys(obj) { | |
var all = {}; | |
var seen = []; | |
checkValue(obj, all, seen); | |
return Object.keys(all); | |
} | |
function checkValue(value, all, seen) { | |
if (Array.isArray(value)) return checkArray(value, all, seen); | |
if (value instanceof Object) return checkObject(value, all, seen); | |
} | |
function checkArray(array, all, seen) { | |
if (seen.indexOf(array) >= 0) return; | |
seen.push(array); | |
for (var i = 0, l = array.length; i < l; i++) { | |
checkValue(array[i], all, seen); | |
} | |
} | |
function checkObject(obj, all, seen) { | |
if (seen.indexOf(obj) >= 0) return; | |
seen.push(obj); | |
var keys = Object.keys(obj); | |
for (var i = 0, l = keys.length; i < l; i++) { | |
var key = keys[i]; | |
all[key] = true; | |
checkValue(obj[key], all, seen); | |
} | |
} | |
var result = inputs.map(getKeys); | |
console.log(result); |
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