JS 数字 转译成 字母

// 1.定义 find 函数，用于返回 在字符串中的 index
var find = function(s1,s2) {
    var len = s1.length;
    if (s1.includes(s2)) {
        for (var i = 0; i < len; i++) {
            var str = s1[i];
            if (str == s2) {
                return i;
            }
        }
    }
    return -1;
}

// 测试函数
var test_find = function() {
    ensure(find(" dad ","a") === 2, '测试1失败');
    ensure(find(" sd","a") === -1, '测试2失败');
    ensure(find("145 "," ") === 3, '测试3失败');
    ensure(find("d5wd","5") === 1, '测试4失败');
}
test_find()


// 2. 数字 转译成 字母
var Numbers = '123456789';
var Letters = 'abcdefghi'; 

var NumsToLetts = function(s) {
    var result = '';
    for (var i = 0; i < s.length; i++) {
        var index = find(Numbers,s[i]);
        result += Letters[index];
        // 字符  用 拼接
    }
    return result;    
}
// 测试 
var test_NumsToLetts = function() {
    ensure(NumsToLetts('123') === 'abc','测试1失败');
    ensure(NumsToLetts('985211') === 'ihebaa','测试2失败');
}
test_NumsToLetts()