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• 句法
• 描述
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

toString() method returns a string representing the source code of the function.

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句法

function.toString()
					

返回值

A string representing the source code of the function.

描述

Function object overrides the toString method inherited from Object ; it does not inherit Object.prototype.toString . For user-defined Function objects, the toString method returns a string containing the source text segment which was used to define the function.

JavaScript calls the toString method automatically when a Function is to be represented as a text value, e.g. when a function is concatenated with a string.

toString() method will throw a TypeError exception ("Function.prototype.toString called on incompatible object"), if its this value object is not a Function 对象。

Function.prototype.toString.call('foo'); // TypeError
					

若 toString() method is called on built-in function objects or a function created by Function.prototype.bind , toString() 返回 native function string which looks like

"function () {\n    [native code]\n}"
					

若 toString() method is called on a function created by the Function constructor, toString() returns the source code of a synthesized function declaration named "anonymous" using the provided parameters and function body.

范例

Comparing actual source code and toString results

function f(){}
									

"function f(){}"
									

class A { a(){} }
									

"class A { a(){} }"
									

function* g(){}
									

"function* g(){}"
									

a => a
									

"a => a"
									

({ a(){} }.a)
									

"a(){}"
									

({ *a(){} }.a)
									

"*a(){}"
									

({ [0](){} }[0])
									

"[0](){}"
									

Object.getOwnPropertyDescriptor({
    get a(){}
}, "a").get
									

"get a(){}"
									

Object.getOwnPropertyDescriptor({
    set a(x){}
}, "a").set
									

"set a(x){}"
									

Function.prototype.toString
									

"function toString() { [native code] }"
									

(function f(){}.bind(0))
									

"function () { [native code] }"
									

Function("a", "b")
									

"function anonymous(a\n) {\nb\n}"
									

规范

浏览器兼容性

图例

完整支持

完整支持

不支持

不支持

另请参阅

• Object.prototype.toString()

• 最后修改： May 21, 2020

相关话题

1. 标准内置对象
2. Function
3. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
4. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
5. 继承：
6. Object
7. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
8. 方法
   1. Object.prototype.__defineGetter__()
   2. Object.prototype.__defineSetter__()
   3. Object.prototype.__lookupGetter__()
   4. Object.prototype.__lookupSetter__()
   5. Object.prototype.hasOwnProperty()
   6. Object.prototype.isPrototypeOf()
   7. Object.prototype.propertyIsEnumerable()
   8. Object.prototype.toLocaleString()
   9. Object.prototype.toSource()
   10. Object.prototype.toString()
   11. Object.prototype.valueOf()
   12. Object.setPrototypeOf()