mirror of
https://github.com/netsurf-browser/netsurf
synced 2024-12-23 04:26:50 +03:00
71 lines
2.7 KiB
JavaScript
71 lines
2.7 KiB
JavaScript
/* Finds the lowest common multiple (LCM) of two numbers */
|
|
function LCMCalculator(x, y) { // constructor function
|
|
var checkInt = function (x) { // inner function
|
|
if (x % 1 !== 0) {
|
|
throw new TypeError(x + " is not an integer"); // throw an exception
|
|
}
|
|
return x;
|
|
};
|
|
this.a = checkInt(x)
|
|
// ^ semicolons are optional
|
|
this.b = checkInt(y);
|
|
}
|
|
// The prototype of object instances created by a constructor is
|
|
// that constructor's "prototype" property.
|
|
LCMCalculator.prototype = { // object literal
|
|
constructor: LCMCalculator, // when reassigning a prototype, set the constructor property appropriately
|
|
gcd: function () { // method that calculates the greatest common divisor
|
|
// Euclidean algorithm:
|
|
var a = Math.abs(this.a), b = Math.abs(this.b), t;
|
|
if (a < b) {
|
|
// swap variables
|
|
t = b;
|
|
b = a;
|
|
a = t;
|
|
}
|
|
while (b !== 0) {
|
|
t = b;
|
|
b = a % b;
|
|
a = t;
|
|
}
|
|
// Only need to calculate GCD once, so "redefine" this method.
|
|
// (Actually not redefinition—it's defined on the instance itself,
|
|
// so that this.gcd refers to this "redefinition" instead of LCMCalculator.prototype.gcd.)
|
|
// Also, 'gcd' === "gcd", this['gcd'] === this.gcd
|
|
this['gcd'] = function () {
|
|
return a;
|
|
};
|
|
return a;
|
|
},
|
|
// Object property names can be specified by strings delimited by double (") or single (') quotes.
|
|
"lcm" : function () {
|
|
// Variable names don't collide with object properties, e.g. |lcm| is not |this.lcm|.
|
|
// not using |this.a * this.b| to avoid FP precision issues
|
|
var lcm = this.a / this.gcd() * this.b;
|
|
// Only need to calculate lcm once, so "redefine" this method.
|
|
this.lcm = function () {
|
|
return lcm;
|
|
};
|
|
return lcm;
|
|
},
|
|
toString: function () {
|
|
return "LCMCalculator: a = " + this.a + ", b = " + this.b;
|
|
}
|
|
};
|
|
|
|
//define generic output function; this implementation only works for web browsers
|
|
function output(x) {
|
|
document.body.appendChild(document.createTextNode(x));
|
|
document.body.appendChild(document.createElement('br'));
|
|
}
|
|
|
|
// Note: Array's map() and forEach() are defined in JavaScript 1.6.
|
|
// They are used here to demonstrate JavaScript's inherent functional nature.
|
|
[[25, 55], [21, 56], [22, 58], [28, 56]].map(function (pair) { // array literal + mapping function
|
|
return new LCMCalculator(pair[0], pair[1]);
|
|
}).sort(function (a, b) { // sort with this comparative function
|
|
return a.lcm() - b.lcm();
|
|
}).forEach(function (obj) {
|
|
output(obj + ", gcd = " + obj.gcd() + ", lcm = " + obj.lcm());
|
|
});
|