Suppose I have a javascript class:
class SomeClass {
constructor() {
this.field1 = [];
this.field2 = 0;
this.field3 = "somestring";
}
someMethod(param1) {
// do some magical stuff
}
}
At some point I have a need to merge two objects, one of them is of SomeClass type.
const obj1 = new SomeClass();
const obj2 = {
field1: [1, 2, 3],
field2: [3, 4, 5],
field3: "other string"
}
const mergedObj = {...obj1, ...obj2};
Now I have lost the someMethod method in mergedObj variable, throwing a TypeError:
mergedObj.someMethod("amazingparam"); //=> Uncaught TypeError: mergedObj.someMethod is not a function
How can I keep the method definitions?
Edit
To be more clear: I would like to create a new object, keep the obj1 and obj2 as they were.
You could use Object.assign it will merge it for you but this will mutate your first object so to solve that problem you could create a clone of you first object on the fly using Object.create like this
class SomeClass {
constructor() {
this.field1 = [];
this.field2 = 0;
this.field3 = "somestring";
}
someMethod(param1) {
console.log('hello')
// do some magical stuff
}
}
const obj1 = new SomeClass();
const obj2 = {
field1: [1, 2, 3],
field2: [3, 4, 5],
field3: "other string"
}
let mergedObj = Object.assign(Object.create(obj1), obj2);
mergedObj.someMethod('')From Josephs answer I worked out a solution.
class SomeAmazingClass{
constructor() {
this.var1 = "";
this.var2 = "";
}
someMethod() {
return this.var1 + this.var2;
}
}
function mergeToSomeAmazingClass(obj1, obj2) {
return Object.assign(new SomeAmazingClass(), obj1, obj2);
}
let a1 = new SomeAmazingClass();
a1.var1 = "OldVar1"
a1.var2 = "OldVar2"
a1.newVar3 = "Yay"
let a2 = {
var1: "NewVar1"
}
let merged = mergeToSomeAmazingClass(a1, a2);
console.log(merged.someMethod());
This keeps the method definitions and keeps the input objects from mutating. Looks a little clumsy, but if there is a better solution I would be happy to see that.
Edit
Updated the merge function.
Simply make your constructor accept optional parameters:
class SomeClass {
constructor({field1 = [], field2 = 0, field3 = "somestring"}) {
Object.assign(this, {field1, field2, field3});
}
someMethod(param1) {
// do some magical stuff
console.log('SomeClass instance here');
}
}
const obj2 = {
field1: [1, 2, 3],
field2: [3, 4, 5],
field3: "other string"
}
const obj1 = new SomeClass(obj2);
obj1.someMethod();
console.log(obj1);