JavaScript code problem with toString()

keble6 · October 12, 2020, 8:45pm

I wanted to use toString(radix) where radix is, say, 2 to display a number in binary.

But the JS window brings up this error: “Expected 0 arguments but got 1”
Screenshot 2020-10-12 at 21.42.36

Is that a bug?

UnsignedArduino · October 12, 2020, 11:49pm

Well, according to w3schools that’s not a bug.

If it’s like that in JavaScript, I’m guessing it would be the same for Typescript too, since TS is based on JS.

In your example, I’m guessing astring would be "3" if you didn’t pass in any parameters to toString.

kwx · October 14, 2020, 1:57am

This should normally work, toString is supposed to take an optional “radix” argument (2 for binary, 16 for hexadecimal): https://github.com/microsoft/TypeScript/blob/master/src/lib/es5.d.ts#L522

interface Number {
    /**
     * Returns a string representation of an object.
     * @param radix Specifies a radix for converting numeric values to strings. This value is only used for numbers.
     */
    toString(radix?: number): string;

However, MakeCode’s Static TypeScript doesn’t appear to understand that and produces the unexpected argument error.

kwx · October 14, 2020, 2:05am

Here’s a quick and inefficient hack, as long as you’re OK with only using it on positive integers:

function bitString (v: number) {
    let out = ""
    let bit = 1
    while (v > 0) {
        out = ((v & bit) ? "1" : "0") + out
        v &= ~bit
        bit *= 2
    }
    return out
}

let a = 244
console.log(bitString(a))

UnsignedArduino · October 14, 2020, 2:20am

Ah, messed up again. Facepalms

But with a little digging around in the PXT repo, found this:

github.com

microsoft/pxt/blob/master/libs/pxt-common/pxt-core.d.ts#L461


    //% shim=String_::fromCharCode weight=1
    //% blockNamespace="text" blockId="stringFromCharCode" block="text from char code %code"
    function fromCharCode(code: number): string;
}

declare interface Number {
    /**
     * Returns a string representation of a number.
     */
    //% shim=numops::toString
    toString(): string;
}

/**
 * Add, remove, and replace items in lists.
*/
//% blockNamespace="Arrays"
declare namespace Array {
    /**
     * Check if a given object is an array.
     */

Looks like it doesn’t take any arguments, unless I’m looking in the wrong spot. (Probably the latter )