Javascript 类型比较
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Javascript Type Comparison
提问by Corey
What is the best way to compare two variables for identical javascript types?:
比较相同 javascript 类型的两个变量的最佳方法是什么？：
I.E.
IE
[] = ['1','2','3']
[] != {}
Number = Number
null = null
etc. etc.
等等等等
回答by adeneo
To just compare types, one would think typeofwould be the right tool
仅比较类型，人们会认为typeof这是正确的工具
typeof [] === typeof ['1','2','3']; // true, both are arrays
Note that null, arrays etc. are of type 'object', which means
请注意null，数组等属于类型'object'，这意味着
typeof [] === typeof null; // is true (both are objects)
typeof [] === typeof {}; // is true (both are objects)
which is expected behaviour.
这是预期的行为。
If you have to specifically check for null, arrays or other things, you could just write a better typeoffunction
如果你必须专门检查空值、数组或其他东西，你可以写一个更好的typeof函数
var toType = function(obj) {
return ({}).toString.call(obj).match(/\s([a-zA-Z]+)/)[1].toLowerCase()
}
Then you could do
那么你可以做
toType([]) === toType(['1','2','3']); // true
toType([]) === toType({}); // false
toType(1) === toType(9999); // true
toType(null) === toType(null); // true
toType(null) === toType([]); // false
回答by Bergi
If you want to distinguish object "types" from each other, it might be a good idea to compare their prototypes:
如果您想将对象“类型”彼此区分开来，比较它们的原型可能是个好主意：
Object.getPrototypeOf([]) === Object.getPrototypeOf([1, 2, 3])
Object.getPrototypeOf({}) !== Object.getPrototypeOf([])
This will however throw if you're not passing in objects, so if you also want to compare the types of primitive values (including null) you will have to do more sophisticated tests:
但是，如果您不传入对象，则会抛出此问题，因此，如果您还想比较原始值的类型（包括null），则必须进行更复杂的测试：
function sameType(a, b) {
var objectA = Object(a) === a,
objectB = Object(b) === b;
if (objectA && objectB)
return Object.getPrototypeOf(a) === Object.getPrototypeOf(b);
else if (!objectA && !objectB)
return typeof a === typeof b;
else
return false;
}
回答by Meredith
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof
typeof 5 === typeof 37
typeof {} === typeof []
回答by sabof
This should work for all "types":
这应该适用于所有“类型”：
function haveSameType(a,b) {
return (a instanceof Array && b instanceof Array) ||
(a === null && b === null) ||
(typeof a === typeof b &&
b !== null &&
a !== null &&
! (a instanceof Array) &&
! (b instanceof Array)
);
}
