primitivesArray = [1,2,3]
primitivesObject = ({x:1, y:2, z: 3})
objectInArray = [{x:1,y:2,z:3}]
nestedObject = ({ x: {z:1}, y: 2})
nestedObjectInArray = [{ x:{z:1} , y: 2}]
nestedObjectWithDates = ({a: {date: new Date()}})
primitivesCopy = Array.from(primitivesArray)
primitivesCopy[0] = 0
primitivesCopy
primitivesArray
testAssignPrimitivesDestination = Object.assign({}, primitivesObject)
testAssignPrimitivesDestination
testAssignPrimitivesDestination.x = 0
primitivesObject
objectInArrayCopyUsingFrom = Array.from(objectInArray)
objectInArrayCopyUsingFrom[0].x = 0
JSON.stringify(objectInArray)
JSON.stringify(objectInArrayCopyUsingFrom)
nestedObjectCopyUsingAssign = Object.assign({}, nestedObject)
nestedObjectCopyUsingAssign.x.z = 0
JSON.stringify(nestedObject)
JSON.stringify(nestedObjectCopyUsingAssign)
md`### \`JSON.parse(JSON.stringify)\` deep copies nested objects from source
`
JSON.stringify(nestedObject)
nestedObjectCopyUsingJSONParse = JSON.parse(JSON.stringify(nestedObject))
nestedObjectCopyUsingJSONParse.x.z = 100
JSON.stringify(nestedObject)
JSON.stringify(nestedObjectCopyUsingJSONParse)
md`### \`JSON.parse(JSON.stringify)\` deep copies array containing object with nested objects
`
nestedObjectInArrayCopyUsingJSONParse = JSON.parse(JSON.stringify(nestedObjectInArray))
nestedObjectInArrayCopyUsingJSONParse[0].x.z = 0
JSON.stringify(nestedObjectInArray)
JSON.stringify(nestedObjectInArrayCopyUsingJSONParse)
md`### Nested \`Date\` objects are stringified in a \`JSON.parse(JSON.stringify)\` deep copy`
nestedObjectWithDatesCopy = deepCopyObjectViaParseStringify(nestedObjectWithDates)
JSON.stringify(nestedObjectWithDatesCopy)
md`### \`Object.create()\` sets source object as prototype of destination object, therefore not affecting the source during modifications`
testObject = ({x:1,y:2,z:3})
testCreate = Object.create(testObject)
//testCreate.x = 0
testCreate.y
testCreate
JSON.stringify(testCreate, Object.keys(testCreate.__proto__))
md`### Utility functions for deep copy of object
- Nested object references are serialized and assigned to a new object
- Deep copy does not refer to existing objects i.e. no sharing of data with original object
- TLDR: Nested objects are duplicated
`
function deepCopyObject(obj) {
let copy = {}
for(let i in obj) {
if(obj[i] && typeof(obj[i] === "object")) {
copy[i] = deepCopyObject(obj[i])
} else {
copy[i] = obj[i]
}
}
return copy
}
deepCopyObjectViaParseStringify = (obj) => {
return JSON.parse(JSON.stringify(obj))
}
plantheidea = import('fast-equals')
plantheidea.deepEqual({ foo: 'bar' }, { foo: 'bar' })
function Circular(value) {
this.present = {
value,
deeply: {
nested: {
reference: this
}
}
}
}
plantheidea.circularDeepEqual(new Circular('foo'), new Circular('foo'))
plantheidea.circularDeepEqual(new Circular('foo'), new Circular('bar'))
testCircularShallow = ['foo']
testCircularShallow.push(testCircularShallow)
plantheidea.circularShallowEqual(testCircularShallow, ['foo', testCircularShallow])
plantheidea.circularShallowEqual(testCircularShallow, [testCircularShallow])
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