编辑代码

const countSubstring = (str, searchStr) => {
    let i = 0;
    let count = 0;
    while (true) {
        let r = str.indexOf(searchStr, i);
        if (r !== -1) {
            [count, i] = [count + 1, r + 1];
        } else return count;
    }
}

const testStr = "hello marry i miss you marry aha marry";
console.log(countSubstring(testStr, 'marry'));