从JavaScript中的嵌套函数返回值 [英] Returning values from nested functions in Javascript

问题描述

考虑此代码(缩短)

function getSecret() {
    db.transaction(
        function (transaction) {
            transaction.executeSql(
                'SELECT * FROM table LIMIT 1;',
                null,
                function(transaction, result) {
                    var row = result.rows.item(0);
                    var secret = row.secret;
                    return secret;
                }, errorHandler
            );
        }
    )
}

我如何将secret的值返回给main函数?我已经阅读了此答案从JavaScript中的嵌套函数返回值

并尝试了

function getSecret() {
    db.transaction(
        function doSql(transaction) {
            transaction.executeSql(
                'SELECT * FROM table LIMIT 1;',
                null,
                function(transaction, result) {
                    var row = result.rows.item(0);
                    var secret = row.secret;
                    return secret;
                }, errorHandler
            );
        }
    )
    return doSql;
}

但是这不起作用.

谢谢！

解决方案

尝试:

function getSecret() {
    var secret = '';

    db.transaction(
        function (transaction) {
            transaction.executeSql(
                'SELECT * FROM table LIMIT 1;',
                null,
                function(transaction, result) {
                    var row = result.rows.item(0);
                    secret = row.secret;
                }, errorHandler
            );
        }
    )

  return secret;
}

Consider this code (shortened)

function getSecret() {
    db.transaction(
        function (transaction) {
            transaction.executeSql(
                'SELECT * FROM table LIMIT 1;',
                null,
                function(transaction, result) {
                    var row = result.rows.item(0);
                    var secret = row.secret;
                    return secret;
                }, errorHandler
            );
        }
    )
}

How would I return the value of secret to the main function? I have read this answer Return value from nested function in Javascript

And tried this

function getSecret() {
    db.transaction(
        function doSql(transaction) {
            transaction.executeSql(
                'SELECT * FROM table LIMIT 1;',
                null,
                function(transaction, result) {
                    var row = result.rows.item(0);
                    var secret = row.secret;
                    return secret;
                }, errorHandler
            );
        }
    )
    return doSql;
}

However this did not work.

Thanks!

解决方案

Try:

function getSecret() {
    var secret = '';

    db.transaction(
        function (transaction) {
            transaction.executeSql(
                'SELECT * FROM table LIMIT 1;',
                null,
                function(transaction, result) {
                    var row = result.rows.item(0);
                    secret = row.secret;
                }, errorHandler
            );
        }
    )

  return secret;
}

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