如何获取字符串之间的相同字符串javascript

function getCommonSubstring(str1, str2) {
  let commonSubstring = "";
  for (let i = 0; i < str1.length; i++) {
    for (let j = 0; j < str2.length; j++) {
      let k = 0;
      while (str1[i + k] === str2[j + k]) {
        k++;
      }
      if (k > commonSubstring.length) {
        commonSubstring = str1.slice(i, i + k);
      }
    }
  }
  return commonSubstring;
}

let str1 = "Hello World";
let str2 = "Hello JavaScript";
let common = getCommonSubstring(str1, str2);
console.log(common); // 输出 "Hello"