Missing initializer in const declaration in node js

Question

I am writing mysql query and kept those records in variable, My requirement is to get access that variable in anywhere so declared it outside of route,but it is showing error like : SyntaxError: Missing initializer in const declaration

const totalQuery = "select name from users";
   
    const totalRecords;
    dbConn.query(totalQuery,function(err,rows)     {
        totalRecords = rows.length
      
    })
    console.log('::'+ totalRecords);
    process.exit();

Error:

SyntaxError: Missing initializer in const declaration

When you create the constant you need to initialize it using =. You can't declare it and then assign a value to it at a later point, for that you would need let (see this MDN article). Note that it also looks like your code will face the following issue: Why is my variable unaltered after I modify it inside of a function? - Asynchronous code reference — Nick Parsons
– Nick Parsons, Commented Dec 30, 2021 at 10:51
console.log('::'+ totalRecords); runs before the code in your callback function: totalRecords = rows.length. So that is why totalRecords is undefined when you log it. Move console.log('::'+ totalRecords); and any other code that relies on rows inside of your callback function. — Nick Parsons
– Nick Parsons, Commented Dec 30, 2021 at 11:04
Please also read: How to return the response from an asynchronous call it looks like a big read, but 100% required knowledge if you want to write a javascript program that deals with asynchronous code (which is what you're trying to do). There is no clear-cut answer to your problem as more context would be needed to get a better idea for what the best option is. I suggest you have a read of the links I've sent to try and get a better idea, you may be able to use Promises here to help, which is also explained the link — Nick Parsons
– Nick Parsons, Commented Dec 30, 2021 at 11:12

p4avinash · Accepted Answer · 2021-12-30 10:53:22Z

7

In javascript, you can't assign value to 'const' later after it's declaration. You're bound to assign the value to const on the declaration line.

If you really need to declare the value some where later, then better go with 'let'

answered Dec 30, 2021 at 10:53

p4avinash

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Indraraj26 · Accepted Answer · 2021-12-30 10:50:11Z

4

Make it let instead of constas you are re-assigning the totalRecords variable

answered Dec 30, 2021 at 10:50

Indraraj26

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2 Comments

user_1234 Over a year ago

but getting undefined value

Rajesh Vyas Jan 23 at 17:05

After I changed to let it's giving this error "Missing semicolon". I swear semicolon is there as mentioned below. let expectedApp: AutomatedApplication = {};

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