如何通过原型传递undefined和null？

Question

我有dynamic code即self creating。在certain conditions下，只有某些类型允许通过某些if statements。

什么当前工作

• 对象
• 布尔
• 数
• 串
• 符号
• 功能

如果代码试图检查它是否是一个null或undefined一切什么打破了代码

1. 空
2. 不确定

分崩离析。或者如果它是null或undefined并且我想检查它是否是一个字符串，它就会崩溃。

我想知道是否有办法通过null或undefined？

演示

演示工作，直到它准备好检查null。

function type(obj) { 
 
    obj = Object.prototype.toString.call(obj).split(' ')[1].replace(']', ''); 
 
    return obj; 
 
} 
 
String.prototype.is = function(what) { 
 
    if (/\b(string|str|s)\b/i.test(what)) { 
 
    return true; 
 
    } 
 
    return false; 
 
}; 
 
Array.prototype.is = function(what) { 
 
    if (/\b(array|arr|a)\b/i.test(what)) { 
 
    return true; 
 
    } 
 
    return false; 
 
}; 
 
Object.prototype.is = function(what) { 
 
    let results = type(this) 
 
    let regex = new RegExp('\\b' + results + '\\b', 'i') 
 
    if (regex.test(what)) { 
 
    return true; 
 
    } 
 
    return false; 
 
}; 
 

 
unknown1 = 'hello world' 
 
unknown2 = /a/g 
 
unknown3 = null // Failed to pass through prototype - suppose to log true 
 
unknown4 = undefined // Failed to pass through prototype - suppose to log false 
 
unknown5 = 9 
 

 
console.log(unknown1.is('string or regexp')) 
 
console.log(unknown2.is('object')) 
 
console.log(unknown3.is('null')) 
 
console.log(unknown4.is('number')) 
 
console.log(unknown5.is('string, number, or object'))

Answer 1

更短，更快的解决方案

也...不破

function type(obj) { 
 
    return Object.prototype.toString.call(obj).split(' ')[1].replace(']', ''); 
 
} 
 

 
function is(obj, what) { 
 
    let regex = new RegExp('\\b(' + type(obj) + ')\\b', 'i'); 
 
    if (regex.test(what)) {return true;} 
 
    return false; 
 
} 
 

 
unknown1 = 'hello world' 
 
unknown2 = /a/g 
 
unknown3 = null 
 
unknown4 = undefined 
 
unknown5 = 9 
 
unknown6 = function name() {} 
 
unknown7 = true 
 
unknown8 = {} 
 

 

 
console.log(is(unknown1, 'a string or function')) 
 
console.log(is(unknown2, 'a regexp')) 
 
console.log(is(unknown3, 'null, regexp, or string')) 
 
console.log(is(unknown4, 'string')) 
 
console.log(is(unknown5, 'string')) 
 
console.log(is(unknown6, 'regexp')) 
 
console.log(is(unknown7, 'a boolean')) 
 
console.log(is(unknown8, 'an object'))