An object literal can also contain setters
defining: a setter
by prefixing the property with set (and make it a function)
let theX = null;
const obj = {
x(newX) { theX = newX; }
};
obj.x = 'the new X';
assert.equal(theX, 'the new X');
must have exactly one parameter
let setterCalledWith = void 0;
const obj = {
x() { // <<<<=== it's not a setter yet!
if (arguments.length === 1) {
setterCalledWith = arguments[0];
}
}
};
assert.equal(obj.x = 'new value', setterCalledWith);
can be a computed property (an expression enclosed in [])
const publicPropertyName = 'x';
const privatePropertyName = '_' + publicPropertyName;
const obj = {
[privatePropertyName]: null,
// write the complete setter to make the assert below pass :)
};
obj.x = 'axe';
assert.equal(obj._x, 'axe');
working with/on the setter
you can use delete to remove the property (including it`s setter)
let setterCalled = false;
const obj = {
set x(param) { setterCalled = true; }
};
// delete the property x here, to make the test pass
obj.x = true;
assert.equal(setterCalled, false);
Links
mdn
docs
Description of all the details of a setter.
spec
"An accessor property associates a key value with one or two accessor functions ..."
spec
The syntax definition of how to write an (accessor) method.
announcement
Announcement of this kata on twitter.