Deep copying array of nested objects in javascript
This question already has an answer here:
You have two main options:
Use JSON.stringify and JSON.parse :
var copy = JSON.parse(JSON.stringify(original));
But I've never liked that. A round-trip through text is inefficient at best, and it won't handle Date , RegExp , undefined , etc. values correctly unless you write a replacer and a reviver.
Use a recursive function, something like this:
var toString = Object.prototype.toString;
function deepCopy(obj) {
var rv;
switch (typeof obj) {
case "object":
if (obj === null) {
// null => null
rv = null;
} else {
switch (toString.call(obj)) {
case "[object Array]":
// It's an array, create a new array with
// deep copies of the entries
rv = obj.map(deepCopy);
break;
case "[object Date]":
// Clone the date
rv = new Date(obj);
break;
case "[object RegExp]":
// Clone the RegExp
rv = new RegExp(obj);
break;
// ...probably a few others
default:
// Some other kind of object, deep-copy its
// properties into a new object
rv = Object.keys(obj).reduce(function(prev, key) {
prev[key] = deepCopy(obj[key]);
return prev;
}, {});
break;
}
}
break;
default:
// It's a primitive, copy via assignment
rv = obj;
break;
}
return rv;
}
var a = [1, {foo: "bar"}, ['a', 'b'], new Date()];
snippet.log(JSON.stringify(a));
var b = deepCopy(a);
snippet.log(JSON.stringify(b));<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
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