CODEWITHSUNDEEP
javascriptfunctioncordovacallbackglobal-variables
Mosayed
Mosayed

Reputation: 47

Javascript global variable not staying changed outside callback function

var IAP_loaded = false; // Global Scope

var IAP_onReady = function(){
     storekit.load(IAP_list, function (products, invalidIds) {
            IAP_loaded = true;
            console.log("1] -- IAP Loaded: "+IAP_loaded); // Outputs true
     });
     console.log("2] -- IAP Loaded: "+IAP_loaded); // Outputs false
     IAP_loaded = true;
     console.log("3] -- IAP Loaded: "+IAP_loaded); // Outputs true
};

console.log("4] -- IAP Loaded: "+IAP_loaded); // Outputs false

For some my global variables aren't staying modified outside the function itself... I created a completely separate function and changed a global variable and it works fine. This just mind baffles me. Any thoughts?

PS. This is a Phonegap 3.0 project and the callback function is from IAP plugin. Found here https://github.com/j3k0/PhoneGap-InAppPurchase-iOS

storekit.load is Asynchronous! Thanks for narrowing it.

2] -- IAP Loaded: false 3] -- IAP Loaded: true 4] -- IAP Loaded: false 1] -- IAP Loaded: true

I get back the response in that order. But it is not Ajax. It's through Objective C, the javascript just handles the responses so it's editable through javascript

Upvotes: 3

Views: 330

Answers (2)

slebetman
slebetman

Reputation: 113906

As with any async code, IAP_loaded is indeed changed to true but not before the code at the bottom executes. To check this, add this test at the bottom after 4:

(function check_IAP(){
    console.log("5] -- IAP Loaded: "+IAP_loaded);
    if (!IAP_loaded) {
        setTimeout(check_IAP,500);
    }
)();

Upvotes: 0

Siddhartha Gupta
Siddhartha Gupta

Reputation: 1168

As suggested IAP (in app purchase) works similar to Ajax. In fact most of phonegap plugins follow the same pattern.

First lets see how plugins works - A call from JS is sent to Obj C file - While Obj C is doing desired calculations other JS code and run simultaneously - After Obj C has completed its calculations the output is sent back to JS via callback

Now lets try to see the code you have provided

var IAP_loaded = false; // Global Scope

var IAP_onReady = function(){
     storekit.load(IAP_list, function (products, invalidIds) {
            IAP_loaded = true;
            console.log("1] -- IAP Loaded: "+IAP_loaded); // Outputs true
     });
     console.log("2] -- IAP Loaded: "+IAP_loaded); // Outputs false
     IAP_loaded = true;
     console.log("3] -- IAP Loaded: "+IAP_loaded); // Outputs true
};

console.log("4] -- IAP Loaded: "+IAP_loaded); // Outputs false

Note - I'm referring to console.log as logs below

Now javascript runs the file is this order

You must be calling 'IAP_onReady' from somewhere, hence

  • log 4 is printed instantly as it is a non-asyn code with output of 'IAP_loaded' as false. You have initiallized 'IAP_loaded' as false

4] -- IAP Loaded: false

  • log 2 is printed instantly as it is a non-asyn code with output of var as false, as still 'IAP_loaded' hasn't been modified yet

2] -- IAP Loaded: false

  • log 3 is printed instantly as it is a non-asyn code, but you have changed the value of 'IAP_loaded' manually to true

3] -- IAP Loaded: true

  • Now after the execution of 'storekit.load' has completed log 1 is printed, and as here value of 'IAP_loaded' manually to true

1] -- IAP Loaded: true

Please try to provide us the complete code, as how the function is called etc.

Upvotes: 1

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