Unexpected token, expected , (8:21)

So I’m working with this code for a blockchain mining class

const Block = require('./Block');
class Blockchain{
    constructor(){
        this.chain = [Blockchain.genesis()];
    }
    addBlock({data}){
        const newBlock = Block.mineBlock([
            lastBlock: this.chain[this.chain.length-1],
            data
        ]);
        this.chain.push();
    }
}
module.exports = Blockchain;

And I keep getting this error Unexpected token, expected , (8:21), for this line:

lastBlock: this.chain[this.chain.length-1],

Any help will be appreciated!

Answer

Try Using this

Block.mineBlock({
lastBlock: this.chain[this.chain.length-1],
data
})

Seems to me like you key:value pairs are not properly formatted.. The code in probably taking

lastBlock: this.chain[this.chain.length-1],

this above line as Key and is expecting a value from data