如何使用Javascript获取作为回调参数传递的函数名

Question

我有以下示例代码来获取函数名，该函数名被传递到回调参数中。

var operation = {
    display : function(fun) {
        console.log('operation "'+ fun.toString() +'" performing' );
        //here i am getting
        /*operation "function () { 
                console.log('operation "subtraction" performed' ); }" performing
        */
        // **instead of entire function i would like to get only method name**
        fun.call();
    },
    addition : function() {
        console.log('operation "addition" performed' );
    },
    subtraction : function() {
        console.log('operation "subtraction" performed' );
    },
    multiplication : function() {
        console.log('operation "multiplication" performed' );
    }
}
operation.display(operation.subtraction);
//Output should be
// operation "subtraction" performing
// operation "subtraction" performed
operation.display(operation.multiplication);
//Output should be
// operation "multiplication" performing
// operation "multiplication" performed
operation.display(operation.addition);
//Output should be
// operation "addition" performing
// operation "addition" performed

Answer 1

您的函数是匿名的；即它们是无名函数表达式。在你得到他们的名字之前，你必须给他们起名字。

var o = {
    foo: function bar() {} // named function expression, name is "bar"
};
function getName(fn) {
    return fn.name;
}
getName(o.foo); // "bar"

然而，这些函数在您的operation对象中确实有相关的键，但是您不能确定某个对象的哪个键是确定的，查找匹配的代码只是猜测，因为值不必是唯一的。

function guessKey(val, obj) {
    var key;
    for (key in obj)
        if (obj[key] === val)
            return key;
    return null;
}
guessKey(o.foo, o); // "foo"

用于IE9+的Function.prototype.name填充(可能也是8；不确定)

if (Function.prototype.name === undefined) { // may be "" so can't use !
    Object.defineProperty(Function.prototype, "name", {
        get: function () {
                var s = Function.prototype.toString.call(this);
                return s.slice(9, s.indexOf('('));
            }
    });
}

Answer 2

function对象包含返回方法名称的" name“属性

更新名称，因为IE没有为使用RegEx的函数实现属性;)这个小函数可以帮助你：

function getFnName(fn) {
  var f = typeof fn == 'function';
  var s = f && ((fn.name && ['', fn.name]) || fn.toString().match(/function ([^\(]+)/));
  return (!f && 'not a function') || (s && s[1] || 'anonymous');
}

这里可以看到：https://gist.github.com/dfkaye/6384439