TypeError: market.FileViewed is not a function while trying to watch event

Question

I want to watch for fileViewed event and it throws TypeError: market.FileViewed is not a function in

marketplace.FileViewed{
           ^

My solidity contract:

pragma solidity ^0.5.0;

contract Marketplace {
    string public name;
    address owner;
    uint public fileCount = 0;
    mapping(uint => File) public files; 


    struct File
    {
        uint id;
        string name;
        address owner;
        address sharedWith;
    }

    mapping(uint => Product) public products;

    struct Product {
        uint id;
        string name;
        address owner;
        address sharedWith;
    }

    event ProductCreated(
        uint id,
        string name,
        address owner,
        address sharedWith
    );

    event FileViewed(
        uint id,
        string name,
        address owner,
        address sharedWith
    );


    constructor() public {
        name = "File Sharing System";
        owner = msg.sender;
    }

    modifier onlyOwner()
    {
        require(owner==msg.sender);
        _;
    }

    function addFile(string memory _name, address _address) onlyOwner public
    {
        fileCount++;
        products[fileCount] = Product(fileCount,_name,owner,_address);
        emit ProductCreated(fileCount, _name, owner, _address);
    }

    function viewFile(uint _id) public view
    {
        Product memory _file = products[_id];
        require(msg.sender==_file.sharedWith,"Not shared with you!!");
        emit FileViewed(fileCount, _name, owner, _address);
    }

}

This is my js:

marketplace.FileViewed(
    function(){
      if(this.state.account!=results.args.sharedWith)
      {
        window.alert("File not shared with you")
      }
      else
      {
        window.alert("File viewed")
      }
    })

  viewFile(id)
  {
    this.setState({loading: true})
    this.state.marketplace.methods.viewFile(id).send({from: this.state.account })
     .once('receipt', (receipt) => {
        this.setState({loading: false})
     })
  }

Answer 1

FileViewed is an event if you are using web3 v1.2 you have to use like this:

marketplace.events.FileViewed({
    fromBlock: 0
}, function (error, event) {
    if (error) {
        console.log("Error: ", error);
    } else {
        console.log("File viewed: ", event);
    }
})

For more details see this: https://web3js.readthedocs.io/en/v1.2.1/web3-eth-contract.html#contract-events