Typescript: VSCode shows me "Type must have a [Symbol.iterator]() method (...) " but Type has it.

[xLama]

I can see that error with this code:

function* numIterator(num: number) {
    var n = parseInt(num.toString()).toString();
    var length = n.length;
    for (var i = length - 1; i >= 0 ; --i){
        yield n.charAt(i);
    }   
}

Number.prototype[Symbol.iterator] = function() {
    return  numIterator(this.valueOf());
}
var num = 2387;
for (var n of num){ // Error in VSCode but It works fine in Chrome
    console.log(n) // 7, 8, 3, 2
}   

[mhegazy]

You are augmenting the Number interface without telling the type system about it, so it does not know that a number now has an iterator. you need to augment the declaration of interface Number to add the iterator declaration, so adding something like this to your file should get rid of the error:

interface Number {
    [Symbol.iterator](): IterableIterator<string>;
}