Heap and Stack | copy target depth

JS variable type is divided into

Value type (basic types): null undefined Number String Boolean

Reference types:

array object

In JS, each requires a data memory space. Memory space has been divided into two types of stack memory (stack) and heap memory (heap) .

Stack memory is typically stored basic data type

There are a = 1

Data stored in the stack memory use stack data structure similar to data structure, following the LIFO principle.

Usually heap memory storing reference data types

var b = {xi: 20}

 

Shallow copy

Shallow copy is a copy of only one

function shallowClone(source) {

var target = {};
for (var i in source) {
if (source.hasOwnProperty(i)) {
target[i] = source[i];
}
}
return target;
}

Deep copy

Unlimited levels copy

json deep copy

function cloneJSON(source) {

    return JSON.parse(JSON.stringify(source));

}

 

= + Deep copy shallow copy recursively  

Drawbacks: for regular objects, func, etc. do not deal with

function clone(source) {

    var target = {};

    for(var i in source) {

        if (source.hasOwnProperty(i)) {

            if (typeof source[i] === 'object') {

                target [i] = clone (source [i]); // Note that

            } else {

                target[i] = source[i];

            }

        }

    }

 

    return target;

}

 

 

 

function cloneJSON(source) { returnJSON.parse(JSON.stringify(source)); }