1, use JSON.parse and JSON.stringify, but it has many issues, major one is can’t handle Date type.
var cloned = JSON.parse(JSON.stringify(objectToClone));
2, refer to this, mainly ideas is loop the properties one by one, and go into children, also need to handle ‘Function’, ‘Symbol’, ‘WeakSet’, etc. all possible data types in JavaScript :
https://stackoverflow.com/questions/122102/what-is-the-most-efficient-way-to-deep-clone-an-object-in-javascript
function clone(obj) {
if (obj === null || typeof (obj) !== 'object' || 'isActiveClone' in obj)
return obj;
if (obj instanceof Date)
var temp = new obj.constructor(); //or new Date(obj);
else
var temp = obj.constructor();
for (var key in obj) {
if (Object.prototype.hasOwnProperty.call(obj, key)) {
obj['isActiveClone'] = null;
temp[key] = clone(obj[key]);
delete obj['isActiveClone'];
}
}
return temp;
}
also there are more examples could refer to, for example this version needs ES6 supports https://stackoverflow.com/questions/40291987/javascript-deep-clone-object-with-circular-references
function deepClone(obj, hash = new WeakMap()) {
// Do not try to clone primitives or functions
if (Object(obj) !== obj || obj instanceof Function) return obj;
if (hash.has(obj)) return hash.get(obj); // Cyclic reference
try { // Try to run constructor (without arguments, as we don't know them)
var result = new obj.constructor();
} catch(e) { // Constructor failed, create object without running the constructor
result = Object.create(Object.getPrototypeOf(obj));
}
// Optional: support for some standard constructors (extend as desired)
if (obj instanceof Map)
Array.from(obj, ([key, val]) => result.set(deepClone(key, hash),
deepClone(val, hash)) );
else if (obj instanceof Set)
Array.from(obj, (key) => result.add(deepClone(key, hash)) );
// Register in hash
hash.set(obj, result);
// Clone and assign enumerable own properties recursively
return Object.assign(result, ...Object.keys(obj).map (
key => ({ [key]: deepClone(obj[key], hash) }) ));
}
Anyway, I recommend to use JavaScript library ‘clone‘ for the deep clone, it could handle circular reference correctly.
If you need to create more complex feature to re-create (serialization) new instance from source object or JSON string (and use TypeScript), I prefer to use this https://github.com/typestack/class-transformer The ‘class-transformer’ doesn’t force you to describe the class with decorator (of course you could do it, and have to if you need rich features), it is good point I prefer to.
