减少此JS程序的资源使用?

Question

我编写了以下JS程序，我使用node从命令行运行该程序。

//step one: create an array of remaining creatures
var remainingCreatures = [];
//some config variables:
var amt = 1000; //amount of creatues generated
var maxhlt = 1000; //max value for creature health stat
var minhlt = 100; //min value for creature health stat
var maxatk = 100; //max value for creature attack stat
var minatk = 1; //min value for creature attack stat
function remove(target) { //helper function to easily remove creatues from the array
var index = remainingCreatures.indexOf(target);
if (index > -1) {
remainingCreatures.splice(index, 1);
}
}
//generate creatures
//each creature has an Attack, Health, and Aggressiveness , as well as Instabillity, the average of the three
//A creature's Instabillity is added to the attack points of its opponent in fights.
for (var i = 0; i < amt; i++) {
var atkVal = Math.floor((Math.random() * maxatk) + minatk);
var hltVal = Math.floor((Math.random() * maxhlt) + minhlt);
var insVal = (atkVal + hltVal) / 2;
remainingCreatures[i] = {num: i, atk: atkVal, hlt: hltVal, ins: insVal, fts: 0, ihlt: hltVal};
}
console.log(amt + " creatues generated, starting melee...");

function fight(cr1, cr2) { //function to handle fighting, randomly creates creature pairs and has them fight
function attack(a, b) {
console.log("[ROUND 1] Creature 1 (#" + a.num + ") is attacking first.");
b.hlt = b.hlt - (a.atk + b.ins);
console.log("[HIT] Creature #" + b.num + " health reduced to " + b.hlt);
if (b.hlt <= 0) {
console.log("[DEATH] Creature #" + b.num + " Eliminated");
remove(b);
} else {
console.log("[ROUND 2] Creature 2 (#" + b.num + ") is attacking second.");
a.hlt = a.hlt - (b.atk + a.ins);
console.log("[HIT] Creature #" + a.num + " health reduced to " + a.hlt);
if (a.hlt <= 0) {
console.log("[DEATH] Creature #" + a.num + " Eliminated");
remove(a);
}
}
}
console.log("[FIGHT] Pair generated: Creature #" + cr1.num + " and Creature #" + cr2.num);
cr1.fts++;
cr2.fts++;
if (cr1.ins <= cr2.ins) {
attack(cr1, cr2);
} else {
attack(cr2, cr1);
}
}

for(;true;) {
if(remainingCreatures.length == 1) break;
fight(remainingCreatures[Math.floor(Math.random() * remainingCreatures.length)], remainingCreatures[Math.floor(Math.random() * remainingCreatures.length)]);
}
console.log(" ");
console.log("[WIN] Creature #" + remainingCreatures[0].num + " has won!");
console.log("Starting array size was " + amt + " creatures")
console.log(remainingCreatures[0]);

出于某种原因，当amt设置为非常大的数字(例如一百万(时，这开始减慢并最终窒息。作为参考，这是将生成并添加到数组中的对象数量 - 正如您可能在代码中看到的那样，该数组被循环了很多。但即使有一百万个对象，每个对象最多也只有大约 80 个字节。该程序正在执行的计算非常基本。

所以我的问题是：为什么运行这个程序如此耗费资源，我怎样才能在不彻底改变程序功能的情况下修复或缓解它？

Answer 1

首先，无论多小，一百万个东西都会对性能产生影响。 另一个问题是你的设计本质上是低效的。

查看您的remove()函数。它首先找到元素的索引，然后将其删除。如果该数组中有一百万个元素，平均而言，它需要将传递的值与500,000 个元素进行比较，以便在删除之前找到它。有一种简单的方法可以解决这个问题;直接传递索引，而不是使用.indexOf。

function fight(ind1, ind2) { //function to handle fighting, randomly creates creature pairs and has them fight
var cr1 = remainingCreatures[ind1];
var cr2 = remainingCreatures[ind2];
function attack(a, b) {
console.log("[ROUND 1] Creature 1 (#" + a.num + ") is attacking first.");
b.hlt = b.hlt - (a.atk + b.ins);
console.log("[HIT] Creature #" + b.num + " health reduced to " + b.hlt);
if (b.hlt <= 0) {
console.log("[DEATH] Creature #" + b.num + " Eliminated");
remove(ind2);
} else {
console.log("[ROUND 2] Creature 2 (#" + b.num + ") is attacking second.");
a.hlt = a.hlt - (b.atk + a.ins);
console.log("[HIT] Creature #" + a.num + " health reduced to " + a.hlt);
if (a.hlt <= 0) {
console.log("[DEATH] Creature #" + a.num + " Eliminated");
remove(ind1);
}
}
}
console.log("[FIGHT] Pair generated: Creature #" + cr1.num + " and Creature #" + cr2.num);
cr1.fts++;
cr2.fts++;
if (cr1.ins <= cr2.ins) {
attack(cr1, cr2);
} else {
attack(cr2, cr1);
}
}

for(;true;) {
if(remainingCreatures.length == 1) break;
fight(Math.floor(Math.random() * remainingCreatures.length), Math.floor(Math.random() * remainingCreatures.length));
}

没有太多其他方法可以轻松提高性能，但仅此一项就足够了。但是，为了使您的代码更具可读性，请考虑替换它：

for(;true;) {
if(remainingCreatures.length == 1) break;
fight(Math.floor(Math.random() * remainingCreatures.length), Math.floor(Math.random() * remainingCreatures.length));
}

有了这个：

// Consider using === and !== as best practice, but not necessary here
while (remainingCreatures.length != 1)
fight(Math.floor(Math.random() * remainingCreatures.length), Math.floor(Math.random() * remainingCreatures.length));

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