Comments (3)
Hi @davidbdeath sorry you are having trouble. That is a general Node.js / JavaScript question, unrelated to this module. You can read more about this in the Node.js guide https://nodejs.org/en/docs/guides/blocking-vs-non-blocking/
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Hi @dougwilson thanks for the quick response. I'm a little bit of a noob. I'm confused why it will output to console.log and push onto the variable locally inside the function but doesn't push onto it globally even though it's the same variable. I read the link but it's still a bit fuzzy. Do i need to create an async function? If you're too busy to explain I wont keep asking. My prof is good at mysql but not so much with javascript.
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Hi @davidbdeath no problem. The issue is that with non-blocking operations that are common in Node.js (typically styled as a "callback"), the code does not run linear top-to-bottom -- the code inside the callback will run at a later time. So thus in the example like
console.log(1)
conn.query('SELECT 1', function () { // this is a callback
console.log(2)
})
console.log(3)
The output will be 1, then 3, then 2. So if you declare a variable at 1, then manipulate it at 2, at 3, you won't see the value, since 3 ran before you did the manipulation, even though reading the file top-to-bottom looks like it may happen before.
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