NodeJs / Javascript
To Deep Copy a variable in Javascript, we have to first check its type – if it is an Array, we then need to clone each element in the array as a new copy and if it is an Object, we have to iterate the keys and assign a cloned copy (deep copy) to the new object. It is primitive type e.g. int, float, we can just return a value – copy by value.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | function clone(Obj) { let buf; // the cloned object if (Obj instanceof Array) { buf = []; // create an empty array var i = Obj.length; while (i --) { buf[i] = clone(Obj[i]); // recursively clone the elements } return buf; } else if (Obj instanceof Object) { buf = {}; // create an empty object for (const k in Obj) { if (obj.hasOwnProperty(k)) { // filter out another array's index buf[k] = clone(Obj[k]); // recursively clone the value } } return buf; } else { return Obj; } } |
function clone(Obj) {
let buf; // the cloned object
if (Obj instanceof Array) {
buf = []; // create an empty array
var i = Obj.length;
while (i --) {
buf[i] = clone(Obj[i]); // recursively clone the elements
}
return buf;
} else if (Obj instanceof Object) {
buf = {}; // create an empty object
for (const k in Obj) {
if (obj.hasOwnProperty(k)) { // filter out another array's index
buf[k] = clone(Obj[k]); // recursively clone the value
}
}
return buf;
} else {
return Obj;
}
}Example usage:
1 2 | var a = [1, 2, "abc", { "a" : [b, 3, 4] }, true]; var b = clone(a); |
var a = [1, 2, "abc", { "a" : [b, 3, 4] }, true];
var b = clone(a);It should be noted that when cloning the elements of array, and the values in an Object, we have to recursively call the function to clone the value – as the element could be another array or Object, or any other types e.g. booleans – who knows how weird the Javascript can get.
–EOF (The Ultimate Computing & Technology Blog) —
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