Delaying the execution of window.location to accommodate AJAX loading

Question

Delaying the execution of window.location to accommodate AJAX loading

I've encountered an issue with my index page while trying to set up a local database before navigating to another page. The problem arises when I have the window.location code enabled - none of the other functions seem to run properly. However, if I disable the window.location code, the other functions work just fine. Any insights on what might be causing this conflict and how I can resolve it to ensure both the functions and the window.locations function as intended? Here's the snippet of code in question:

<script>
        var db = window.openDatabase("DB1", "", "DB", 1024 * 1000)
            CreateDB(); //Creates local database tables
            loadRouteList(); //Queries web server database using AJAX and inserts Routes
            window.location = 'Application.html';
</script>

Functions Utilized:

function CreateDB() {
    db.transaction(function (tx) {
        tx.executeSql('CREATE TABLE IF NOT EXISTS Routes(id INTEGER PRIMARY KEY, routeID TEXT, customerID TEXT, stopSeq TEXT, driverID TEXT)', []);
    });
};
function loadRouteList() {
var dataObject = {
    postDesignator: 'routes',
};
$.ajax({
    url: 'http://url.php',
    data: dataObject,
    dataType: 'json',
    type: 'post',
    success: function (Result) {
        for (var i = 0, len = Result.records.length; i < len; ++i) {
            var route = Result.records[i].record;
            insertRoute(route.routeID, null, null, null);
        }
    }
});
}

javascript ajax window.location

Answer 1

Answer №1

Implement callback functions for improved code functionality:

<script>
    var database = window.openDatabase("DB1", "", "DB", 1024 * 1000);
    initiateDatabaseTables(); // Function to create local database tables
    fetchListOfRoutes(function() { window.location = 'Application.html'} );
</script>

List of Functions Utilized:

function initiateDatabaseTables() {
    database.transaction(function (tx) {
        tx.executeSql('CREATE TABLE IF NOT EXISTS Routes(id INTEGER PRIMARY KEY, routeID TEXT, customerID TEXT, stopSeq TEXT, driverID TEXT)', []);
    });
};
function fetchListOfRoutes(callback) {
    var requestData = {
        postDesignator: 'routes',
    };
    $.ajax({
        url: 'http://url.php',
        data: requestData,
        dataType: 'json',
        type: 'post',
        success: function (result) {
            for (var i = 0, length = result.records.length; i < length; ++i) {
                var routeData = result.records[i].record;
                insertRoute(routeData.routeID, null, null, null);
            }
            // Callback execution after successful ajax request completion
            if(callback) { callback(); }
        }
    });
}

Answer 2

Implement callback functions for improved code functionality:

<script>
    var database = window.openDatabase("DB1", "", "DB", 1024 * 1000);
    initiateDatabaseTables(); // Function to create local database tables
    fetchListOfRoutes(function() { window.location = 'Application.html'} );
</script>

List of Functions Utilized:

function initiateDatabaseTables() {
    database.transaction(function (tx) {
        tx.executeSql('CREATE TABLE IF NOT EXISTS Routes(id INTEGER PRIMARY KEY, routeID TEXT, customerID TEXT, stopSeq TEXT, driverID TEXT)', []);
    });
};
function fetchListOfRoutes(callback) {
    var requestData = {
        postDesignator: 'routes',
    };
    $.ajax({
        url: 'http://url.php',
        data: requestData,
        dataType: 'json',
        type: 'post',
        success: function (result) {
            for (var i = 0, length = result.records.length; i < length; ++i) {
                var routeData = result.records[i].record;
                insertRoute(routeData.routeID, null, null, null);
            }
            // Callback execution after successful ajax request completion
            if(callback) { callback(); }
        }
    });
}

Answer 3

Answer №2

When dealing with AJAX, it is important to remember that it is asynchronous in nature. This means that if you execute functions without waiting for them to complete, your code will continue running and may lead to unexpected results such as changing the location before necessary tasks are finished. To ensure all requests are completed before moving on, you need to make sure the code inside your functions handles this properly. If you share your code, we can provide assistance.

EDIT

In my opinion, a good approach is to implement a callback function in your code:

function CreateDB() {
    db.transaction(function (tx) {
        tx.executeSql('CREATE TABLE IF NOT EXISTS Routes(id INTEGER PRIMARY KEY, routeID TEXT, customerID TEXT, stopSeq TEXT, driverID TEXT)', []);
    });
    //if even this piece of code is async you should read docs and check how to call a function after the query executed
};
function loadRouteList(callback) {
    var dataObject = {
        postDesignator: 'routes',
    };
    $.ajax({
        url: 'http://url.php',
        data: dataObject,
        dataType: 'json',
        type: 'post',
        success: function (Result) {
            for (var i = 0, len = Result.records.length; i < len; ++i) {
                var route = Result.records[i].record;
                insertRoute(route.routeID, null, null, null);
            }
            if(callback) {
                callback();
            }
        }
    });
}

Then, you can incorporate it like this:

var db = window.openDatabase("DB1", "", "DB", 1024 * 1000)
    CreateDB(); //Creates local database tables
    loadRouteList(function() {
        window.location = 'Application.html';
    });

Answer 4

When dealing with AJAX, it is important to remember that it is asynchronous in nature. This means that if you execute functions without waiting for them to complete, your code will continue running and may lead to unexpected results such as changing the location before necessary tasks are finished. To ensure all requests are completed before moving on, you need to make sure the code inside your functions handles this properly. If you share your code, we can provide assistance.

EDIT

In my opinion, a good approach is to implement a callback function in your code:

function CreateDB() {
    db.transaction(function (tx) {
        tx.executeSql('CREATE TABLE IF NOT EXISTS Routes(id INTEGER PRIMARY KEY, routeID TEXT, customerID TEXT, stopSeq TEXT, driverID TEXT)', []);
    });
    //if even this piece of code is async you should read docs and check how to call a function after the query executed
};
function loadRouteList(callback) {
    var dataObject = {
        postDesignator: 'routes',
    };
    $.ajax({
        url: 'http://url.php',
        data: dataObject,
        dataType: 'json',
        type: 'post',
        success: function (Result) {
            for (var i = 0, len = Result.records.length; i < len; ++i) {
                var route = Result.records[i].record;
                insertRoute(route.routeID, null, null, null);
            }
            if(callback) {
                callback();
            }
        }
    });
}

Then, you can incorporate it like this:

var db = window.openDatabase("DB1", "", "DB", 1024 * 1000)
    CreateDB(); //Creates local database tables
    loadRouteList(function() {
        window.location = 'Application.html';
    });

Delaying the execution of window.location to accommodate AJAX loading

Answer №1

Answer №2

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