ADD COLUMN IF NOT EXISTS with Node and Mysql

I know three ways to solve this problem.

1. With a stored procedure.
2. Ignoring the error and continue.
3. Working an algorithm in backend

I would resolve with Node in my backend. So I did this.

let exist = false
connection.query(`
     SELECT IF(count(*) = 1, 'Exist','Not Exist') AS result
     FROM information_schema.columns
     WHERE table_schema = 'database'
       AND table_name = 'table_name'
       AND column_name = '${columnName}';
    `,
    (error, results, fields) => {
       if (error) throw error
       else if (results[0].result === 'Exist') {
         exist = true
       }
     }
)
if (!exist) {
   connection.query(`
      ALTER TABLE ofertas
      ADD COLUMN ${columnName} VARCHAR(255);
      `,
      (error, result, fields) => {
        if (error) throw error
      }
  )
}

This code not work. I belive the problem is async because exist always is true. I use mysql module