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<title>5、构造函数有__proto__属性，实例对象没有prototype 属性，原型对象有__proto__属性</title>
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<script>
function fn() {
}
console.log(fn.prototype); // {constructor: ?}
// {constructor: ?, __defineGetter__: ?, __defineSetter__: ?, hasOwnProperty: ?, __lookupGetter__: ?,?…}
console.log(fn.prototype.__proto__); //
console.log(fn.__proto__); // ? () { [native code] }
f1 = new fn()
console.log(f1.__proto__ === fn.prototype); // true
console.log(f1.prototype); // undefined
</script>
274 构造函数有__proto__属性，实例对象没有prototype 属性，原型对象有__proto__属性
原文：https://www.cnblogs.com/jianjie/p/12242411.html