no-new-func
禁止使用 Function
对象的 new
运算符
可以在运行时使用 Function
构造函数在 JavaScript 中从字符串创建函数,例如:
¥It’s possible to create functions in JavaScript from strings at runtime using the Function
constructor, such as:
var x = new Function("a", "b", "return a + b");
var x = Function("a", "b", "return a + b");
var x = Function.call(null, "a", "b", "return a + b");
var x = Function.apply(null, ["a", "b", "return a + b"]);
var x = Function.bind(null, "a", "b", "return a + b")();
由于调试和阅读这些类型的函数很困难,许多人认为这是一种不好的做法。此外,内容安全策略 (CSP) 指令可能不允许使用 eval()
和类似的方法从字符串创建代码。
¥This is considered by many to be a bad practice due to the difficulty in debugging and reading these types of functions. In addition, Content-Security-Policy (CSP) directives may disallow the use of eval()
and similar methods for creating code from strings.
规则详情
¥Rule Details
引发此错误是为了突出使用不良做法。通过将字符串传递给 Function
构造函数,你需要引擎以调用 eval
函数时必须的方式解析该字符串。
¥This error is raised to highlight the use of a bad practice. By passing a string to the Function
constructor, you are requiring the engine to parse that string much in the way it has to when you call the eval
function.
此规则的错误代码示例:
¥Examples of incorrect code for this rule:
/*eslint no-new-func: "error"*/
var x = new Function("a", "b", "return a + b");
var x = Function("a", "b", "return a + b");
var x = Function.call(null, "a", "b", "return a + b");
var x = Function.apply(null, ["a", "b", "return a + b"]);
var x = Function.bind(null, "a", "b", "return a + b")();
var f = Function.bind(null, "a", "b", "return a + b"); // assuming that the result of Function.bind(...) will be eventually called.
此规则的正确代码示例:
¥Examples of correct code for this rule:
/*eslint no-new-func: "error"*/
var x = function (a, b) {
return a + b;
};
何时不使用
¥When Not To Use It
在更高级的情况下,你确实需要使用 Function
构造函数。
¥In more advanced cases where you really need to use the Function
constructor.
版本
此规则是在 ESLint v0.0.7 中引入。