Typescripts

What is it currently printing in your console log statement?

Can you share what the printout is?

Your if statement is this,startTime. It should be this.startTime. your CodeBlockEvent might also need a hz. In front of it. There is also a space between this. and connectCodeBlockEvents. It also looks like your console.log is not displaying a string. It should be enclosed in ""

What IDE are you using?

I'm currently on my phone. If your still having issues when I get back I'll take a look is Visual Studios Community and post it here for you.

Bellow I have the code with some notes. I tested my changes it in a blank world and it printed both for me.

import * as hz from 'horizon/core';

class TimeSpentScriptts extends hz.Component<typeof TimeSpentScriptts> {
    static propsDefinition = {};

    private startTime: number = 0;
    start() {
        // make sure there are no empty spaces
        // code is case sensitive
        // double check spelling
        // do not forget the hz if you are importing * as hz.
        // startTime is not declared anywhere. I declared it for you, see below the propsDefinition.
        // double check for accidental , instead of .
        // Dont forget to wrap your strings with "" or ``. Since you are using ${} use ``
        // Cannot assign a number to null

        // your code
        // this. ConnectCodeBlockEvent(this.entity, CodeBlockEvent.OnPlayerEnterWorld,(player:player) => { this.startTime = Date.now();

        // this is how it should look
        this.connectCodeBlockEvent(this.entity, hz.CodeBlockEvents.OnPlayerEnterWorld, (player: hz.Player) => {
            this.startTime = Date.now();
            console.log("startTime: " + this.startTime);
        });

        // your code
        //this.connectCodeBlockEvent(this.entity, CodeBlockEvents.OnPlayerexitWorld, (player: player) => {
            //if(this,startTime !== null) {
            //const timeSpent =(Date.now()
            //- this.startTime) / 1000;
            //console.log(Player ${player.name.get()} spent ${timespent}
            //seconds in the world.);
            //this.startTime = null;
            //}
        //});

        // this is how it should look
        this.connectCodeBlockEvent(this.entity, hz.CodeBlockEvents.OnPlayerExitWorld, (player: hz.Player) => {
            if (this.startTime !== null) {
                const timeSpent = (Date.now() - this.startTime) / 1000;
                console.log(`Player ${player.name.get()} spent ${timeSpent } seconds in the world.`);
                this.startTime = 0;
            }
        });
    }
}
hz.Component.register(TimeSpentScriptts);

This is what your code looks like in my IDE (Visual Studio Community). I'm not sure what you are using to write code but if you use Visual Studio Community or even Visual Studio Code it should tell you if there is an error with your code with the red lines. It will go a long way in helping you learn proper syntax and prevent syntax errors/bugs.