Why does a JavaScript function automatically convert a binary number when I pass it as an argument? [duplicate]

Question

I guess I can format it back. I'm just interested in why it's happening.

function test(d){
 console.log(d) // 151028224
}
console.log(test(00001100101000))

Answer 1

By default, any number literally written with a zero at the beginning is considered as octal (base 8) number representation, and then, when you show back any number with console.log, it is written as its base 10 representation.

console.log(05)
console.log(06)
console.log(07)
console.log(010)
console.log(011)

It's recommended to avoid this in code, because it can lead to confusions :

if the number contains the digits 8 or 9, it cannot be a base-8 number, and thus treated as base 10 !

console.log(05)
console.log(06)
console.log(07)
console.log(08) // Yiiik !
console.log(09) // Yiiik !
console.log(010)
console.log(011)