Published
Edited
Nov 18, 2020
2 stars
// Constructor functions are not called with new
// They take some form of specification or config object as an argument
// although could take any set of arguments as they are just normal functions
function constructor(spec) {
// Declare variables scoped to this function
// All these are inside the function's scope and are inaccessibe from outside
let
// Destructure and process items coming from the spec
// potentially assinging defaults and/or error checking as required
{member} = spec,
// Call other constructors and extra data/behaviors
{other} = otherConstructor(spec),
// Build methods that close over everything available in its containing block
method = function () {
// member, other, method, spec, etc. are available here, e.g.
return member + other;
};
// Anything that forms part of the public interface is put in the outgoing object
// This object is then frozen, creating a hard, uncoruptible interface
return Object.freeze({
method,
other,
});
}
// This is another constructor to demonstrate calling constructors in the above
function otherConstructor(spec) {
return Object.freeze({
other: 42,
});
}
obj = constructor({ member: 1 });
obj.other;
obj.other = 0;
obj.method();
function chainWith(returnedObj, fluentMethod) {
return function (...args) {
fluentMethod(...args);
return returnedObj;
};
}
function conditionalChainWith(returnedObj, interceptObj, fluentMethod) {
return function (...args) {
const result = fluentMethod(...args);
return result === interceptObj ? returnedObj : result;
};
}
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