如何评估用户在web应用程序中输入的代码
How can I evaluate a users code input in my web application
我正在尝试构建一个演示站点来帮助其他人学习代码。我在评估来自代码的用户输入时遇到问题。我知道我可以使用eval()函数，但我会有很多例子，拥有许多eval()函数似乎不是很理想或简洁。如果我使用eval()，实现最佳实践的最佳方式是什么？
或者，有没有一种方法可以实现一个简单的编译器或通用函数，并指定一个按钮点击来运行所述函数，该函数将在编辑器中评估代码并将其显示在页面上的某个位置。
我目前正在使用Ace作为我的编辑器。也许他们的api中有一个函数可以做到这一点，但我找不到。我也知道我可以使用代码镜像，但也不确定他们的解决方案。如有任何帮助，我们将不胜感激。
这里有一个指向JSBIN的链接（注意：代码编辑器没有显示在这里，因为我不需要库
这是一个链接到我有功能版本的网站。
如果你需要看到代码，我已经发布在下面：
HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>Learn to Code with Codesmith</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/font-awesome/4.4.0/css/font-awesome.min.css">
<link href='http://fonts.googleapis.com/css?family=Open+Sans:400;300' rel='stylesheet' type='text/css'>
<link href='style.css' rel='stylesheet'>
<style type="text/css" media="screen">
</style>
</head>
<body>
<!-- <div class="page-wrapper">
<a class="btn trigger" href="javascript:;">Click Me!</a>
</div> -->
<div class="modal-wrapper">
<div class="modal">
<div class="head">
<a class="btn-close trigger" href="javascript:;"></a>
</div>
<div class="content">
<form class="" action="" method="post">
<input id="username" type="text" name="name" value="" placeholder="Username">
<input id="password" type="text" name="name" value="" placeholder="Password">
<button id="login-submit" type="button" name="button">LOGIN</button>
</form>
</div>
</div>
</div>
<div class="menu">
<!-- Menu icon -->
<div class="icon-close">
<img src="http://s3.amazonaws.com/codecademy-content/courses/ltp2/img/uber/close.png">
</div>
<!-- Menu -->
<ul>
<li class="main-cat"><a href="#">FOUNDATIONS</a></li>
<ul>
<li class="sub-cat"><a href="#">Intro to Javascript</a></li>
<li class="sub-cat"><a href="#">Algorithms</a></li>
<li class="sub-cat"><a href="#">Data Structures</a></li>
<li class="sub-cat"><a href="#">Data Types</a></li>
<li class="sub-cat"><a href="#">Syntax</a></li>
<li class="sub-cat"><a href="#">Variables</a></li>
<li class="sub-cat"><a href="#">Strings</a></li>
<li class="sub-cat"><a href="#">Arrays</a></li>
<li class="sub-cat"><a href="#">Objects</a></li>
<li class="sub-cat"><a href="#">Functions</a></li>
<li class="sub-cat"><a href="#">Scope</a></li>
</ul>
<li class="main-cat"><a href="#">Intermediate</a></li>
<li class="main-cat"><a href="#">Advanced</a></li>
</ul>
</div>
<!-- Main body -->
<div class="nav">
<button class="sign-up" type="button" name="button" onclick="">SIGN UP</button>
<!-- <a class="btn trigger" href="javascript:;">Click Me!</a> -->
<!-- <button class="login trigger" type="button" name="button" onclick="">LOGIN</button> -->
<a class="login trigger" type="button" name="button" onclick="" href="javascript:;">LOGIN</a>
<div class="icon-menu">
<i class="fa fa-bars"></i>
Menu
</div>
<div class="video">
<iframe width="560" height="315" src="https://www.youtube.com/embed/JeyH_8pWVJ4" frameborder="0" allowfullscreen></iframe>
</div>
<div class="code-snippet sandbox">
<pre id="editor"> // Write your code here and when finished, click the run button below...
<!-- function greeting() {
console.log("Hello, World!");
} -->
</pre>
<div id="run-code">
<button class="run-code" type="button" name="button" onclick="evaluate()" >RUN</button>
</div>
</div>
<!-- <textarea class="code-eval" name="output" rows="8" cols="40"></textarea> -->
<!-- <a class="jsbin-embed" href="http://jsbin.com/iwovaj/73/embed?html,output&height=315px&width=700px"></a>
<script src="http://static.jsbin.com/js/embed.js"></script> -->
<script src="src-noconflict/ace.js" type="text/javascript" charset="utf-8"></script>
<script>
var editor = ace.edit("editor");
editor.setTheme("ace/theme/chaos");
editor.session.setMode("ace/mode/javascript");
editor.session.getLength(true);
document.getElementById('editor').style.fontSize='14px';
editor.getSession().setUseWrapMode(true);
editor.setHighlightActiveLine(true);
</script>
<script src="sandbox.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script></script>
<script src="app.js"></script>
</body>
</html>
CSS
html, body{
width:100%;
height:100%;
margin:0;
}
body {
overflow: hidden;
left: 0;
margin: 0;
overflow: hidden;
position: relative;
}
#editor {
margin: 0;
position: relative;
top: 0;
bottom: 0;
left: 0;
right: 0;
width: 700px;
height: 315px;
}
.code-snippet {
margin:0 auto;
display: block;
float: right;
padding: 40px 40px;
}
.run-code {
background-color: #1fbad6;
border: 3px solid #1fbad6;
padding: 10px 20px;
margin-top: 40px;
margin-bottom: 40px;
outline: none;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-align:center;
text-decoration:none;
color:#fff;
border-radius:5px;
float: right;
}
.video {
position: relative;
float: left;
padding: 40px 40px;
}
/*.jsbin-embed {
position: relative;
float: right;
width: 700px;
height: 315px;
padding: 40px 40px;
}*/
/* Initial menu */
.menu {
background: #202024 url('http://s3.amazonaws.com/codecademy-content/courses/ltp2/img/uber/black-thread.png') repeat left top;
left: -285px; /* start off behind the scenes */
height: 100%;
position: fixed;
width: 285px;
}
/* Basic styling */
.nav {
/*background-image: url('http://s3.amazonaws.com/codecademy-content/courses/ltp2/img/uber/bg.png');*/
background-color: #202020;
height: 75px;
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
}
.menu ul {
border-top: 1px solid #636366;
list-style: none;
margin: 0;
padding: 0;
}
.menu li {
font-family: 'Open Sans', sans-serif;
line-height: 45px;
padding-bottom: 3px;
padding-left: 20px;
padding-top: 3px;
}
.main-cat {
border-bottom: 1px solid #636366;
color: #03A3EA;
}
.sub-cat li {
font-family: 'Open Sans', sans-serif;
line-height: 45px;
padding-bottom: 3px;
padding-left: 20px;
padding-top: 3px;
}
.menu a {
color: #fff;
font-size: 15px;
text-decoration: none;
text-transform: uppercase;
}
.icon-close {
cursor: pointer;
padding-left: 10px;
padding-top: 10px;
}
.icon-menu {
color: #1fbad6;
cursor: pointer;
font-family: 'Open Sans', sans-serif;
font-size: 20px;
padding-bottom: 25px;
padding-left: 25px;
padding-top: 25px;
text-decoration: none;
text-transform: uppercase;
}
.icon-menu i {
margin-right: 5px;
}
.login {
position: relative;
float: right;
margin-top: 18px;
margin-right: 20px;
padding: 5px 15px;
font-size: 18px;
color: #1fbad6;
background: none;
border: 3px solid #1fbad6;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-align:center;
text-decoration:none;
border-radius:5px;
}
.sign-up {
position: relative;
float: right;
margin-top: 18px;
margin-right: 20px;
padding: 5px 15px;
font-size: 18px;
color: #1fbad6;
background: none;
border: 3px solid #1fbad6;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-align:center;
text-decoration:none;
border-radius:5px;
}
/* ============ MODAL ========== */
.page-wrapper{
width:100%;
height: 100%;
/* //background:url(http://i.imgur.com/2ZgHKbQ.jpg) center no-repeat;
//background-size:cover;*/
}
.blur{
-webkit-filter: blur(5px);
-moz-filter: blur(5px);
-o-filter: blur(5px);
-ms-filter: blur(5px);
filter: blur(5px);
}
a.btn{
width:150px;
display:block;
margin:-25px 0 0 -75px;
padding:1em 0;
position:absolute;
top:50%; left:50%;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-align:center;
text-decoration:none;
color:#fff;
border-radius:5px;
background:rgba(217,67,86,1);
}
.modal-wrapper{
width:100%;
height:100%;
position:fixed;
top:0; left:0;
background:rgba(64,64,64,1);
visibility:hidden;
opacity:0;
-webkit-transition: all 0.25s ease-in-out;
-moz-transition: all 0.25s ease-in-out;
-o-transition: all 0.25s ease-in-out;
transition: all 0.25s ease-in-out;
z-index: 999;
}
.modal-wrapper.open{
opacity:1;
visibility:visible;
}
.modal{
width:600px;
height:400px;
display:block;
margin:50% 0 0 -300px;
position:relative;
top:50%; left:50%;
background:#fff;
opacity:0;
-webkit-transition: all 0.5s ease-in-out;
-moz-transition: all 0.5s ease-in-out;
-o-transition: all 0.5s ease-in-out;
transition: all 0.5s ease-in-out;
}
.modal-wrapper.open .modal{
margin-top:-200px;
opacity:1;
}
.head{
width:90%;
height:32px;
padding:1.5em 5%;
overflow:hidden;
background:#01bce5;
}
.btn-close{
width:32px;
height:32px;
display:block;
float:right;
}
.btn-close::before, .btn-close::after{
content:'';
width:32px;
height:6px;
display:block;
background:#fff;
}
.btn-close::before{
margin-top:12px;
-webkit-transform:rotate(45deg);
-moz-transform:rotate(45deg);
-o-transform:rotate(45deg);
transform:rotate(45deg);
}
.btn-close::after{
margin-top:-6px;
-webkit-transform:rotate(-45deg);
-moz-transform:rotate(-45deg);
-o-transform:rotate(-45deg);
transform:rotate(-45deg);
}
.content{
padding:5%;
}
#username {
width: 95%;
background: none;
border: 3px solid #1fbad6;
padding: 12px;
margin-bottom: 40px;
outline: none;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-decoration:none;
border-radius:5px;
color: #202020;
}
#password {
width: 95%;
background: none;
border: 3px solid #1fbad6;
padding: 12px;
margin-bottom: 40px;
outline: none;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-decoration:none;
border-radius:5px;
color: #202020;
}
#login-submit {
background-color: #1fbad6;
border: 3px solid #1fbad6;
padding: 10px 20px;
margin-bottom: 40px;
outline: none;
font:1.125em 'Arial', sans-serif;
font-weight:700;
text-align:center;
text-decoration:none;
color:#fff;
border-radius:5px;
float: right;
}
JAVASCRIPT
var main = function() {
/* Push the body and the nav over by 285px over */
$('.icon-menu').click(function() {
$('.menu').animate({
left: "0px"
}, 100);
$('body').animate({
left: "285px"
}, 100);
});
/* Then push them back */
$('.icon-close').click(function() {
$('.menu').animate({
left: "-285px"
}, 100);
$('body').animate({
left: "0px"
}, 100);
});
};
/* ========== Evaluate Code ========== */
var app = {};
// go through the application and find every single instance of a div
// with the class of 'sandbox'
app.bootstrap = function() {
var sandboxes = document.getElementsByClassName('sandbox');
// for each sandbox, run the createSandbox function
[].forEach.call(sandboxes, app.createSandbox);
};
// given a parent element, find the first textarea inside and
// create a sandbox around it
app.createSandbox = function(parent) {
var textarea = parent.getElementsByTagName('textarea')[0],
// create an instance of Sandbox using this textarea
sandbox = Sandbox(textarea);
parent.appendChild(sandbox.label);
};
// when the DOM loads bootstrap the application
window.addEventListener('load', app.bootstrap);
// Sandbox class
// This class is based around a textarea element, which will contain
// the code. However, it could just as easily be the DOM element for
// an Ace/Codemirror editor.
function Sandbox(textarea) {
var sandbox = {};
// create a label to show output
sandbox.label = document.createElement('label');
sandbox.label.setAttribute('class', 'output');
sandbox.label.addEventListener('click', evaluate);
// evaluate code whenever there is input into the textarea
textarea.addEventListener('input', evaluate);
sandbox.textarea = textarea;
// initial resize and evaluation
resize();
evaluate();
// resize to within the appropriate height for the textarea
function resize() {
var scrollHeight = textarea.scrollHeight;
if(scrollHeight > Sandbox.MAX_HEIGHT) {
height = Sandbox.MAX_HEIGHT;
} else if(scrollHeight < Sandbox.MIN_HEIGHT) {
height = Sandbox.MIN_HEIGHT;
} else {
height = scrollHeight;
}
textarea.style.height = height + 'px';
}
// evaluate the code within the textarea
function evaluate() {
// get the code
var src = textarea.value,
// create a console proxy (for logging to the label)
console = Sandbox.consoleProxy(sandbox.label);
// clear the output first
sandbox.label.innerText = '';
// try the eval and catch errors to send to the console
try {
/* jshint ignore:start */
eval(src);
/* jshint ignore:end */
} catch(err) {
console.error(err);
}
}
return sandbox;
}
// config
Sandbox.MAX_HEIGHT = 500;
Sandbox.MIN_HEIGHT = 50;
// A function which spoofs the native console object, by writing
// text to output elements, rather than the dev tools console.
Sandbox.consoleProxy = function(element) {
return {
log: function(message) {
message = [].join.call(arguments, ' ');
element.innerText += (message + ''n');
element.setAttribute('disabled', false);
// write to the original console too
console.log.apply(console, arguments);
},
error: function(message) {
element.setAttribute('disabled', true);
element.innerText = message;
}
};
};
/* ========== Modal ========== */
$('.trigger').click(function() {
$('.modal-wrapper').toggleClass('open');
$('.page-wrapper').toggleClass('blur');
return false;
});
$(document).ready(main);
eval是运行代码的默认方式。由于其与安全漏洞的关系，它的声誉并不太好，然而，如果这不是一个问题，用户将在沙盒中运行自己的代码，这正是eval的设计初衷，而且它做得很好。
为Javascript实现一个简单的编译器是一项不小的任务，但是，如果你确信这是正确的方法，那么在解析和评估代码时，你可以利用esprima等开源项目来为你做一些繁重的工作。
我为过去的一个项目开发了一个通用代码评估小部件，只需使用<textarea>和eval。它支持对控制台的日志和错误进行沙盒处理。浏览代码可能会有所帮助。
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