How to access variable outside of query block?-CodePudding

I want to use the for loop outside of the query but it is printing empty.

sql = 'SELECT * FROM people';
let currMarker = [];

db.all(sql, [], (err,rows) => {
    if (err) return console.error(err.message);
    
    currMarker = rows;

    for (let i = 0; i < currMarker.length; i  ) {
        console.log(currMarker[i].name);
        console.log(currMarker[i].username);
    }
});

I want to use it like :

sql = 'SELECT * FROM people';
let currMarker = [];

db.all(sql, [], (err,rows) => {
    if (err) return console.error(err.message);
    
    currMarker = rows;
});

for (let i = 0; i < currMarker.length; i  ) {
    console.log(currMarker[i].name);
    console.log(currMarker[i].username);
}

CodePudding user response：

Here's a solution.

sql = 'SELECT * FROM people';

let currMarker = [];

const queryFunc = () =>{
    return new Promise((resolve, reject)=>{
        db.all(sql, [], (err,rows) => {
            if (err) return console.error(err.message);
            
            currMarker = rows;
            resolve();
        });
    });
};

queryFunc().then((val)=>{
    for (let i = 0; i < currMarker.length; i  ) {
        console.log(currMarker[i].name);
        console.log(currMarker[i].username); 
    }
});