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所以，我试图为字母替换密码做一个小算法，但当程序试图打印结果时遇到了问题。对铬reutrns JS的控制台“遗漏的类型错误：无法读取空的特性‘的innerHTML’”上线55，77和99Javascript函数返回未捕获TypeError：无法读取属性'innerHTML'null
这里是代码：
<!DOCTYPE html>
<html>
<head>
<title>Alphabetical Subtitution Cipher</title>
</head>
<body>
<h1>Alphabetical Subtitution Cipher</h1>
<input type="text" id ="txt"></input>
<button type="button" onclick="encrypt()">Encrypt!</button>
<button type="button" onclick="">Decrypt!</button>
<button type="button" onclick="res.innerHTML = ''; ">Clear!</button>
<div id="result"></div>
<script>
var letters = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'];
var numbers = ['1', '2', '3', '4', '5', '6', '7', '8', '9', '0'];
var symbols = ['~', '!', '@', '#', '$', '%', '^', '&', '*', '(', ')', '_', '-', '=', '+', '[', '{', ']', '}', '/', ';', ':', '"', '|', '.', ',', '<', '>', '?'];
var txt = document.getElementById('txt');
var res = document.getElementById('res');
function encrypt() {
var spl = txt.value.toLowerCase().split("");
for(var i = 0; i < spl.length; i++) { //goes through the spl array
if (spl[i] == ' ') { //if the string is a space
res.innerHTML += ' '; //prints space
}
else {
for(var j = 0; j < letters.length; j++) { //goes through the letters array
if(spl[i] == letters[j]) { //if the spl array string equals to the letter array string
var ecip = (j * i) + spl.length;
if (ecip > letters.length) { //if ecip is out of the array
ecip = ecip - letters.length;
res.innerHTML += letters[ecip];
}
else {
res.innerHTML += letters[ecip];
}
}
}
for(var k = 0; k < numbers.length; k++) { //goes through the numbers array
if (spl[i] == numbers[k]) { //if the spl array string equals to the numbers array currently checked string
var ecip = (k * i) + spl.length;
if (ecip > numbers.length) { //if ecip is out of the array
ecip = ecip - numbers.length;
res.innerHTML += numbers[ecip];
}
else {
res.innerHTML += numbers[ecip];
}
}
}
for(var l = 0; l < symbols.length; l++) { //runs through the symbols array
if(spl[i] == symbols[l]) { //if the spl array string equals to the symbols array string
var ecip = (l * i) + spl.length;
if (ecip > symbols.length) { //if ecip is out of the array
ecip = ecip - symbols.length;
res.innerHTML += symbols[ecip];
}
else {
res.innerHTML += symbols[ecip];
}
}
}
}
}
}
</script>
</body>
</html>
我会强烈，如果你欣赏它可以帮助我并解释我犯了什么错误！谢谢！