这对你的问题正确吗？

const arrString = ["beginning=beginner", "leaves=leave", "sound=sounds"];

let string = "its beginner in the sounds leave";

arrString.forEach((mapString) => {
  const stringArr = mapString.split("=");
  string = string.replace(stringArr[1], stringArr[0]);
});

console.log("string", string);
// "its beginning in the sound leaves"

如果你在空间上妥协的话，你也可以在没有嵌套循环的情况下这样做。
下面是一个解决方案，它为替换值创建一个Map对象，并使用数组方法（如map()、forEach()、join()）和字符串方法（如split()）。

const arrString = ["beginning=beginner", "leaves=leave", "sound=sounds"];

let string1 = "its beginner in the sounds leave beginner";
const replaceObj = {};
const arrBreaks = arrString.forEach(x => {
let els = x.split("=");
replaceObj[els[1]] = els[0]; });

const ans = string1.split(' ').map((x) => {
  if(x in replaceObj) { let val = replaceObj[x]; delete val; return val; }
  return x;
}).join(' ');

console.log(ans);