我做了一个很好的元组实现。此解决方案允许数组解构以及基本类型检查。
const Tuple = (function() {
function Tuple() {
// Tuple needs at least one element
if (arguments.length < 1) {
throw new Error('Tuple needs at least one element');
}
const args = { ...arguments };
// Define a length property (equal to the number of arguments provided)
Object.defineProperty(this, 'length', {
value: arguments.length,
writable: false
});
// Assign values to enumerable properties
for (let i in args) {
Object.defineProperty(this, i, {
enumerable: true,
get() {
return args[+i];
},
// Checking if the type of the provided value matches that of the existing value
set(value) {
if (typeof value !== typeof args[+i]) {
throw new Error('Cannot assign ' + typeof value + ' on ' + typeof args[+i]);
}
args[+i] = value;
}
});
}
// Implementing iteration with Symbol.iterator (allows for array destructuring as well for...of loops)
this[Symbol.iterator] = function() {
const tuple = this;
return {
current: 0,
last: tuple.length - 1,
next() {
if (this.current <= this.last) {
let val = { done: false, value: tuple[this.current] };
this.current++;
return val;
} else {
return { done: true };
}
}
};
};
// Sealing the object to make sure no more values can be added to tuple
Object.seal(this);
}
// check if provided object is a tuple
Tuple.isTuple = function(obj) {
return obj instanceof Tuple;
};
// Misc. for making the tuple more readable when printing to the console
Tuple.prototype.toString = function() {
const copyThis = { ...this };
const values = Object.values(copyThis);
return `(${values.join(', ')})`;
};
// conctat two instances of Tuple
Tuple.concat = function(obj1, obj2) {
if (!Tuple.isTuple(obj1) || !Tuple.isTuple(obj2)) {
throw new Error('Cannot concat Tuple with ' + typeof (obj1 || obj2));
}
const obj1Copy = { ...obj1 };
const obj2Copy = { ...obj2 };
const obj1Items = Object.values(obj1Copy);
const obj2Items = Object.values(obj2Copy);
return new Tuple(...obj1Items, ...obj2Items);
};
return Tuple;
})();
const SNAKE_COLOR = new Tuple(0, 220, 10);
const [red, green, blue] = SNAKE_COLOR;
console.log(green); // => 220