if (typeof v === 'function') {
    // do something
}

如果你正在寻找一个简单的解决方案:

 function isFunction(value) {
   return value instanceof Function
}

jQuery(3.3版已弃用)参考

$.isFunction(functionName);

AngularJS参考

angular.isFunction(value);

Lodash参考

_.isFunction(value);

强调参考

_.isFunction(object); 

Node.js自v4.0.0参考版起已弃用

var util = require('util');
util.isFunction(object);

从节点v0.11开始，你可以使用标准的util函数:

var util = require('util');
util.isFunction('foo');

if (typeof v === 'function') {
    // do something
}

有几种方法，所以我将把它们都总结一下

Best way is: function foo(v) {if (v instanceof Function) {/* do something */} }; Most performant (no string comparison) and elegant solution - the instanceof operator has been supported in browsers for a very long time, so don't worry - it will work in IE 6. Next best way is: function foo(v) {if (typeof v === "function") {/* do something */} }; disadvantage of typeof is that it is susceptible to silent failure, bad, so if you have a typo (e.g. "finction") - in this case the if will just return false and you won't know you have an error until later in your code The next best way is: function isFunction(functionToCheck) { var getType = {}; return functionToCheck && getType.toString.call(functionToCheck) === '[object Function]'; } This has no advantage over solution #1 or #2 but is a lot less readable. An improved version of this is function isFunction(x) { return Object.prototype.toString.call(x) == '[object Function]'; } but still lot less semantic than solution #1