What is the best technique for accessing information from protractor's promises series?

Question

What is the best technique for accessing information from protractor's promises series?

My function successfully retrieves the index of an element with the text "check" and prints it using console.log:

function getIndex() {
    return element.all(by.css(".palette__item.ng-scope>span")).then(function (colorList) {
        colorList.forEach(function (elem, index) {
            elem.getText().then(function (text) {
                if (text == "check") {
                    console.log(index);
                    return index;
                }
            });
        });
    });
}

Despite numerous attempts, I have been unable to retrieve the data from it successfully. My latest approach was:

var res = null;
webDriver.promise.fullyResolved(getIndex()).then(function (index) {
    res = index;
});
console.log(res);

Even after initializing the `res` value inside the function to guarantee promise resolution, it still returns null.

I suspect an error in the `getIndex()` function, possibly related to the placement of the return operator. I am in need of assistance as I am out of ideas on how to make it work. Any help is greatly appreciated.

javascript angularjs testing protractor

Answer 1

Answer №1

You might be overcomplicating things a bit. Instead of using the "forEach" method, consider utilizing the reduce() method:

function determineIndex() {
    return element.all(by.css(".palette__item > span")).reduce(function (accumulator, currentElement, currentIndex) {
        return currentElement.getText().then(function (text) {
            if (text == "check") {
                return currentIndex;
            } 
        });
    }, -1);
}

How to use:

determineIndex().then(function (index) {
    console.log(index);
});

Also, avoid using the ng-scope class in your locators as it is a specific Angular technical class without much significance for your locator.

Answer 2

You might be overcomplicating things a bit. Instead of using the "forEach" method, consider utilizing the reduce() method:

function determineIndex() {
    return element.all(by.css(".palette__item > span")).reduce(function (accumulator, currentElement, currentIndex) {
        return currentElement.getText().then(function (text) {
            if (text == "check") {
                return currentIndex;
            } 
        });
    }, -1);
}

How to use:

determineIndex().then(function (index) {
    console.log(index);
});

Also, avoid using the ng-scope class in your locators as it is a specific Angular technical class without much significance for your locator.

Answer 3

Answer №2

Although I am unable to debug at the moment, the following solution may resolve the issue:

function findIndex() {
    return element
            .all(by.css(".palette__item.ng-scope>span"))
            .then((colorList) => { 
              // obtain text for all elements
              return Promise.all( colorList.map( (el) = el.getText() ) ); 
            })
            .then((colorList) => {
              // both text and index are necessary
              return colorList.map( (el, ind) => [el, ind] )
              // filter out elements with text "check"
                              .filter( (elArr) => elArr[0] == 'check' )
              // discard text and keep only the index
                              .map( (elArr) => elArr[1] );
            })
}

The main issue lies in mixing functions that return promises with other iterator-functions. This results in the loss of the promise context when the return statement is executed.

Answer 4

Although I am unable to debug at the moment, the following solution may resolve the issue:

function findIndex() {
    return element
            .all(by.css(".palette__item.ng-scope>span"))
            .then((colorList) => { 
              // obtain text for all elements
              return Promise.all( colorList.map( (el) = el.getText() ) ); 
            })
            .then((colorList) => {
              // both text and index are necessary
              return colorList.map( (el, ind) => [el, ind] )
              // filter out elements with text "check"
                              .filter( (elArr) => elArr[0] == 'check' )
              // discard text and keep only the index
                              .map( (elArr) => elArr[1] );
            })
}

The main issue lies in mixing functions that return promises with other iterator-functions. This results in the loss of the promise context when the return statement is executed.

Answer 5

Answer №3

Here are a few points to consider:

Firstly, the variable is initialized outside of the promise but its value is assigned within the promise. While this is acceptable, the placement of the console.log() statement in your code is important. If it remains at the bottom of the code, it may run before the promise resolves, resulting in the variable 'res' being null.

Have you tried logging the value of res inside the promise?

Regarding the getIndex function, why are you using promises within the forEach loop? Have you considered restructuring the code like this:

function getIndex() {
    return element.all(by.css(".palette__item.ng-scope>span")).then(function (colorList) {
        colorList.forEach(function (elem, index) {
                var temp = elem.getText()
                if (temp == "check") {
                    console.log(index);
                    return index
            });
        });
    });
}

Based on the information provided, this is the best advice I can offer. It is important to understand the differences between asynchronous and synchronous code.

Answer 6

Here are a few points to consider:

Firstly, the variable is initialized outside of the promise but its value is assigned within the promise. While this is acceptable, the placement of the console.log() statement in your code is important. If it remains at the bottom of the code, it may run before the promise resolves, resulting in the variable 'res' being null.

Have you tried logging the value of res inside the promise?

Regarding the getIndex function, why are you using promises within the forEach loop? Have you considered restructuring the code like this:

function getIndex() {
    return element.all(by.css(".palette__item.ng-scope>span")).then(function (colorList) {
        colorList.forEach(function (elem, index) {
                var temp = elem.getText()
                if (temp == "check") {
                    console.log(index);
                    return index
            });
        });
    });
}

Based on the information provided, this is the best advice I can offer. It is important to understand the differences between asynchronous and synchronous code.

What is the best technique for accessing information from protractor's promises series?

Answer №1

Answer №2

Answer №3

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