javascript

sort-array-by-array.js

    // Sort by fitness
    //     JSON.stringify([[5, 3], [2, "string"], [4, 1]].sort())
    //     "[[2,"string"],[4,1],[5,3]]"
    //     `a` and `b` are sorted by `a.toString()` - `b.toString()`
    //     See also: http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.11
    //     所以是不靠谱的：
    //     ["190", (2000000000000000000000000).toString(), (1000000000000000000000000000000000000).toString()].sort()
    //     ["190", "1e+36", "2e+24"]

    this.population = this.population.map(function(individual) {
        return [self.fitness(individual), individual];
    }).sort().map(function(elem) {
        return elem[1];
    });

sort里的坑.js

[200000000000000000, 10000000000000000000000000000].sort();
// => [1e+28, 200000000000000000]
// 因为 es 标准规定这个必须要通过 toString() 来排序
// http://www.ecma-international.org/ecma-262/5.1/#sec-9.8.1
// http://www.ecma-international.org/ecma-262/5.1/#sec-15.4.4.11

[200000000000000000, 10000000000000000000000000000].sort(function(a, b) {return a - b;});
// => [200000000000000000, 1e+28]

Use this:

    var fitness = this.population.map(function(individual, i) {
        return {index: i, fitness: self.fitness(individual)};
    }).sort(function(a, b) {
        return b.fitness - a.fitness;
    });

    var population = fitness.map(function(e, i) {
        return this.population[i];
    });