DOP_price.js

const { ethers } = require('ethers');
const provider = new ethers.providers.JsonRpcProvider('https://bsc-dataseed.binance.org/');

const BEP20 = {
    BUSD: '0xe9e7cea3dedca5984780bafc599bd69add087d56',
    DOP: '0x844fa82f1e54824655470970f7004dd90546bb28',
};

const Contract = {
    router: new ethers.Contract(
        '0x10ED43C718714eb63d5aA57B78B54704E256024E', // pancake V2 router
        ['function getAmountsOut(uint amountIn, address[] memory path) public view returns (uint[] memory amounts)'],
        provider
    )
}

getExchangeRate(BEP20.DOP, BEP20.BUSD).then(price => {
    console.log(`1 DOP =`, price, 'BUSD');
});

async function getExchangeRate(tokenIn, tokenOut){
    const amounts = await Contract.router.getAmountsOut(ethers.utils.parseUnits('1', 18), [tokenIn, tokenOut]);
    return amounts[1].toString()/1e18;
}