This is a simple operation, but it seems to be tricky. so here is a simple class with a static method.
export class MyClass {
static foo = {"key" : "value"};
static bar = JSON.parse(JSON.stringify(MyClass.foo));
MyClass.bar["key"] = "newVal";
}
considering that foo is a very large object that wants to copy in another static variable bar. after coping I want to update some properties.
but this doesn't seem to work, getting error, Unknown keyword or identifier. Did you mean 'class'?
MyClass.bar["key"] = "newVal"; this is invalid.
what's the issue here? how to update the static member just after assigning.
You can use a static initialisation block:
class MyClass {
static foo = {"key" : "value"};
static bar = JSON.parse(JSON.stringify(MyClass.foo));
static {
MyClass.bar["key"] = "newVal";
}
}
console.log(MyClass.foo);
console.log(MyClass.bar);Or do the whole initialisation in the static block:
class MyClass {
static foo = {"key" : "value"};
static {
//`this` in a static block refers to the class
this.bar = JSON.parse(JSON.stringify(MyClass.foo));
this.bar["key"] = "newVal";
}
}
console.log(MyClass.foo);
console.log(MyClass.bar);An alternative would be an immediately invoked function expression (IIFE) for environments that do not support static blocks:
class MyClass {
static foo = {"key" : "value"};
static bar = (() => {
const obj = JSON.parse(JSON.stringify(MyClass.foo));
obj["key"] = "newVal";
return obj;
})();
}
console.log(MyClass.foo);
console.log(MyClass.bar);Or just put the update after the class declaration:
class MyClass {
static foo = {"key" : "value"};
static bar = JSON.parse(JSON.stringify(MyClass.foo));
}
MyClass.bar["key"] = "newVal";
console.log(MyClass.foo);
console.log(MyClass.bar);