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JavaScript

Jamie Moore
Jamie Moore
3,997 Points
Posted by Jamie Moore
Jamie Moore
3,997 Points

Why does 'token.push' not require the 'this' keyword?

Following along with this video, and the majority of it makes sense, but one thing i'm struggling with, is why does the 'token.push' in the createTokens method not require 'this'?

The code in question:

class Player {
    constructor(name, id, color, active = false) {
        this.name = name;
        this.id = id;
        this.color = color;
        this.active = active;
        this.tokens = this.createTokens(21);
    }

    /**
     * Creates token objects for player
     * @param   {integer}   num - Number of token objects to be created
     * @return  {array}     tokens - an array of new token objects
     */

    createTokens(num){
        for (let i = 0; i < num; i++) {
            let token = new Token(i,this);
            tokens.push(token);
        }
        return tokens;
    }
}

1 Answer

denisegagne
denisegagne
24,704 Points
denisegagne
denisegagne
24,704 Points

This is because tokens is limited to the scope of the function. The createTokens() function should really include a secondary "let" variable like below, but the browser will sometimes recognize the intention and create the variable for you. Especially if "tokens" is the ID of another element on a page.

this.tokens doesn't "exist" until after the function is returned.

    createTokens(num){
        let tokens = [];
        for (let i = 0; i < num; i++) {
            let token = new Token(i,this);
            tokens.push(token);
        }
        return tokens;
    }
Jamie Moore
Jamie Moore
3,997 Points
Jamie Moore
Jamie Moore
3,997 Points

Thanks, that makes perfect sense. I'd completely overlooked the tokens array being created within the function.