let x = 2,
y = x = typeof y;
console.log(x); // >> 'string'Could you explain why the value of x ends up being a string in this code snippet?
let x = 2,
y = x = typeof y;
console.log(x); // >> 'string'Could you explain why the value of x ends up being a string in this code snippet?
The variable is being hoisted and initialized with the value of 'undefined'.
var a, b;
a = 2,
b = typeof a;
console.log(a, typeof a);
console.log(b, typeof b);Upon running this code once, the variable z will hold the value of "undefined". When executed multiple times, z will contain the value "string".
Explanation:
var z = 1, y = z = typeof y;
console.log(z); // >> 'string'
The sequence of events is as follows:
z to 1. This makes the value of z equal to 1.y, resulting in "undefined" since y has no defined value.z = "undefined", making its value "undefined".y = "undefined", causing y to be "undefined".z, which will show undefined.When run again, the outcome changes:
z as 1. This gives z a value of 1.typeof y as "string" because y now holds "undefined".z = "string", leading to z being "string".y = "string", resulting in y containing "string".z, displaying string.The reason why the string undefined is returned is because the value of typeof y is assigned to variable z, but at that point in time, y has not been defined yet. It's important to note that the typeof operator always returns a string indicating the type of the operand.
It is perfectly normal to receive the output as string in this situation. This happens because you are assigning the result of the typeof y expression to variable z, which will always return a string representation of the data type.
For example:
var a = typeof undefined;
console.log(a); // This will output "undefined", a string value.
What's going on beneath the surface of your code is as follows:
var z = undefined;
var y = undefined;
z = 1;
console.log(z) // z is now 1
z = typeof y
console.log(z) // undefined
console.log(y) // undefined
y = z
console.log(z) // undefined
console.log(y) //undefined
Don't be fooled by the result being undefined and treat it as a string.
console.log(typeof undefined) // "undefined"
console.log(typeof "undefined") // string
Undefined is a type unless specifically assigned to "undefined"; in this case, using quotes makes it a string.
In order to get "string" printed, try console.log(typeof z), which will output string because z has been assigned the value "undefined" enclosed in quotes rather than just undefined.
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