app.wifi is the instance of Wi-Fi API, which provide functions to access Wi-Fi from your app. In order to use this API, you need to add these permissions to you package.json file.
android.permission.ACCESS_WIFI_STATE
android.permission.CHANGE_WIFI_STATE
A working example of Wi-Fi API
new Promise(function(resolve, reject){
    app.wifi.enable();
    setTimeout(resolve, 5000);
}).then(function(){
    available_networks = app.wifi.getScanResult();
    available_networks.forEach(function(network){
        if(network.SSID == "test"){
            app.wifi.connect(network.SSID, "");
        }
    });
});
app.wifi.enable()Enables the Wi-Fi of android device.
An example of above code:
app.wifi.enable();
app.wifi.disable()Disables the Wi-Fi of android device, if already enable.
An example of above code:
app.wifi.disable();
app.wifi.connect(SSID, password)SSID String
    SSID of the network which you want to connect.password String
    password of the network which you want to connect.NOTE: If you want to connect with open network then provide password = ""
Connects Wi-Fi to the provided SSID network.
An example of above code:
app.wifi.connect("test", "");
app.wifi.disconnect()Disconnects the Wi-Fi to currenty connected network.
An example of above code:
app.wifi.disconnect();
app.wifi.getScanResults()Returns Array of JSON Objects with details of currently available wifi networks.
An example of above code:
let networks = app.wifi.getScanResults();
networks.forEach(function(network){
    console.log(network.SSID);
})
app.wifi.getState()Returns the current state of Wi-Fi.
An example of above code:
console.log(app.wifi.getState());
app.wifi.isEnabled()Returns true if Wi-Fi is enable otherwise false.
An example of above code:
console.log(app.wifi.isEnabled());