如何比较两个字符串，找到差异，用javascript返回缺失的单词

Question

let main = "i am really calm at this moment";
let sub = "am this";
function missingWords () {

let mainArr = main.split(" ");
let subArr = sub.split(" ");

return mainArr.toLowerCase().filter( x => !subArr.toLowerCase.includes(x));
};

console.log(missingWords());

Answer 1

数组没有toLowerCase()函数。如果你想让数组中的所有元素都是小写的，你应该先把字符串转换成小写，然后用一个空格分隔。

let main = "i am really calm at this moment";
let sub = "am this";
function missingWords() {
let mainArr = main.toLowerCase().split(" ");
let subArr = sub.toLowerCase().split(" ");

return mainArr.filter(x => !subArr.includes(x));
};
console.log(missingWords());

Answer 2

我看不出有任何理由拆分这两个字符串。'includes'不仅可以用于数组，还可以用于字符串

function missingWords(mainString,subString) {
const lowerMainString = mainString.toLowerCase();
const lowerSubString = subString.toLowerCase();
return lowerMainString.split(" ").filter(x => !lowerSubString.includes(x));
};
missingWords("i am really calm at this moment", "am this");