javascript - 在 javascript 函数的参数中放置一个值

Question

我似乎无法弄清楚这个函数中 match 的目的是什么？。我尝试删除它，结果是

NaN 1, NaN 2, and NaN 101

var stock = "1 lemon, 2 cabbages, and 101 eggs";
function minusOne(amount, unit) {
  amount = Number(amount) - 1;
  if (amount == 1) // only one left, remove the 's'
    unit = unit.slice(0, unit.length - 1);
  else if (amount == 0)
    amount = "no";
  return amount + " " + unit;
}
console.log(stock.replace(/(\d+) (\w+)/g, minusOne));

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下面给出的代码的输出

no lemon, 1 cabbage, and 100 eggs

var stock = "1 lemon, 2 cabbages, and 101 eggs";

function minusOne(match, amount, unit) {
  amount = Number(amount) - 1;
  if (amount == 1) // only one left, remove the 's'
    unit = unit.slice(0, unit.length - 1);
  else if (amount == 0)
    amount = "no";
  return amount + " " + unit;
}
console.log(stock.replace(/(\d+) (\w+)/g, minusOne));

<强> Code Reference

Answer 1

String.prototype.replace() 函数采用可选函数参数 here .

这只是因为它是函数的内置行为，如果您删除 match ，它会将 match 替换为 amount (在你的情况下)。这根本没有意义。