/
3_30.js
129 lines (104 loc) · 2.5 KB
/
3_30.js
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class Wheel {
constructor(rim, tire) {
this._rim = rim;
this._tire = tire;
}
get rim() { return this._rim; }
get tire() { return this._tire; }
diameter() {
return this.rim + (this.tire * 2);
}
}
/**
* Using fixed args
*/
class GearUsingFixedArgs {
constructor(chainring, cog, wheel) {
this._chainring = chainring;
this._cog = cog;
this._wheel = wheel;
}
get chainring() { return this._chainring; }
get cog() { return this._cog; }
get wheel() { return this._wheel; }
// ...
gear_inches() {
return this.ratio() * this.wheel.diameter();
}
ratio() {
return this.chainring / this.cog;
}
}
console.log(new GearUsingFixedArgs(
52,
11,
new Wheel(26, 1.5)
).gear_inches());
// => 137.0909090909091
/*
* Using "hash"
*
* NOTE: In JavaScript, this might more commonly be referred to as using an
* object parameter. The idea is to make the caller explicitly name the
* parameters when they call the method.
*/
class GearUsingHash {
constructor(args) {
this._chainring = args['chainring']; // NOTE: could instead be `args.chainring`
this._cog = args['cog'];
this._wheel = args['wheel'];
}
get chainring() { return this._chainring; }
get cog() { return this._cog; }
get wheel() { return this._wheel; }
// ...
gear_inches() {
return this.ratio() * this.wheel.diameter();
}
ratio() {
return this.chainring / this.cog;
}
}
console.log(new GearUsingHash({
chainring: 52,
cog: 11,
wheel: new Wheel(26, 1.5)
}).gear_inches());
// => 137.0909090909091
/*
* Using "keyword args"
*
* NOTE: Here, we're using destructuring on the constructor's parameters to
* achieve something similar to the Ruby keyword argument example.
*
* SEE: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment
*/
class GearUsingKeywordArgs {
constructor({ chainring, cog, wheel }) {
this._chainring = chainring
this._cog = cog;
this._wheel = wheel;
}
get chainring() { return this._chainring; }
get cog() { return this._cog; }
get wheel() { return this._wheel; }
// ...
gear_inches() {
return this.ratio() * this.wheel.diameter();
}
ratio() {
return this.chainring / this.cog;
}
}
console.log(new GearUsingKeywordArgs({
cog: 11,
chainring: 52,
wheel: new Wheel(26, 1.5)
}).gear_inches());
// => 137.0909090909091
console.log(new GearUsingKeywordArgs({
wheel: new Wheel(26, 1.5),
chainring: 52,
cog: 11
}).gear_inches());
// => 137.0909090909091