How to make this interact with metamask

I’ve been trying to make my contract be callable by metamask (so a popup will occur telling the user to confirm) but it does not seem to work, heres what I have come up with so far. Can anyone give me tips or advice on how to proceed? Thanks!

  // Check if Web3 has been injected by the browser:
  if (typeof web3 !== 'undefined') {
    // You have a web3 browser! Continue below!
    startApp(web3);
  } else {
     // Warn the user that they need to get a web3 browser
     // Or install MetaMask, maybe with a nice graphic.
  }

})
const Eth = require('ethjs-query')
const EthContract = require('ethjs-contract')

function startApp(web3) {
  const eth = new Eth(web3.currentProvider)
  const contract = new EthContract(eth)
  initContract(contract)
}
const abi = [{
  "constant": false,
  "inputs": [
    [
            {
                "internalType": "address",
                "name": "_tokenTake",
                "type": "address"
            },
            {
                "internalType": "uint256",
                "name": "_amount",
                "type": "uint256"
            },
            {
                "internalType": "address",
                "name": "_tokenReturn",
                "type": "address"
            },
            {
                "internalType": "bytes",
                "name": "_userData",
                "type": "bytes"
      } 
    ],
  ]
}]
const address = 'insert contract address'
function initContract (contract) {
}