这是什么官方 JavaScript 解析器 does:
// In the second stage, we run the text against regular expressions that look
// for non-JSON patterns. We are especially concerned with '()' and 'new'
// because they can cause invocation, and '=' because it can cause mutation.
// But just to be safe, we want to reject all unexpected forms.
// We split the second stage into 4 regexp operations in order to work around
// crippling inefficiencies in IE's and Safari's regexp engines. First we
// replace the JSON backslash pairs with '@' (a non-JSON character). Second, we
// replace all simple value tokens with ']' characters. Third, we delete all
// open brackets that follow a colon or comma or that begin the text. Finally,
// we look to see that the remaining characters are only whitespace or ']' or
// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.
if (/^[\],:{}\s]*$/.
test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@').
replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {
// In the third stage we use the eval function to compile the text into a
// JavaScript structure. The '{' operator is subject to a syntactic ambiguity
// in JavaScript: it can begin a block or an object literal. We wrap the text
// in parens to eliminate the ambiguity.
j = eval('(' + text + ')');
...
除了内置的JSON解析支持在现代浏览器中,这就是所有(基于库的)安全 JSON 解析器所做的事情(即,之前的正则表达式测试eval
).
安全图书馆(除了官方的json2实现之外)
原型的isJSON功能。
穆托尔斯JSON.decode函数(再次,通过之前的正则表达式测试eval).
不安全的库:
dojo's fromJson does not提供安全eval
ing. 这是他们的完整实现(减去注释):
dojo.fromJson = function(json) {
return eval("(" + json + ")");
}
jQuery 不提供安全的 JSONeval
'ing,但请参阅官方插件的secureEvalJSON函数(第 143 行)。