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:

在线运行
/*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:

在线运行
/*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。

资源

ESLint 中文网
粤ICP备13048890号