量角器用getText（）进行诺言解析

Question

I call the getText() function like so and then try to resolve the promise but cant get the string value later.

var textFromElement = someElement.getText().then(function(text){return text})
var splittedText = textFromElement.split(" ")

How can I get the text for later use?

Answer 1

What you don't understand is how the javascript compiler deals with promises.

This is how the compiler looks at your code;

var textFromElement = someElement.getText().then(function(text){return text})
var splittedText = textFromElement.split(" ")

1 - All variable are created at the top of the function scope regardless of where you assign it.

var textFromElement; (= undefined)
var splittedText; (= undefined)

2 - Does the minimum amount of work it can get away with for each line and moves to the next line.

testFromElement = {promise element object};
splittedText = {promise element object}.split(" "); (= undefined)//This what you don't want.

3 - Starts at the top and does more minimal work on unresolved lines.

testFromElement = {promise getText object};

4 - Starts at the top and does more minimal work on unresolved lines.

testFromElement = "text text";

In short it assigns splittedText three step before you want it to.

Good example:

var splittedText;
it("should get split text", function(done) {
  someElement.getText().then(function(textFromElement){
    splittedText = textFromElement.split(" ");
    done();
  })
})

1 - All variable are created at the top of the function scope regardless of where you assign it.

var splittedText; (= undefined)

2 - Only work is done inside this function until done() is called

it("should get split text", function(done) {

3 - Does the minimum amount of work it can get away with for each line and moves to the next line.

someElement = {promise element object};

4 - Starts at the top of the function and does more minimal work on unresolved lines.

someElement.getText() = {promise getText object};

5 - Starts at the top of the function and does more minimal work on unresolved lines.

textFromElement = "text text";
splittedText = textFromElement.split(" "); (["text","text"]);
done();  //the compiler can now to work outside this function

Answer 2

Your problem is that you are assigning the resolution of .then() method to your variable, not callback which you are providing as a parameter to it.

All in all protractor/jasmine comes with mechanism for asyncronous tests.

Here you got ES6 example.

it('some description', (done) => {
    someElement.getText().then(text => {
        var splittedText = text.split(" ");
        done();
    });
});

And ES5:

it('some description', function(done) => {
    someElement.getText().then(function(text){
        var splittedText = text.split(" ");
    }).finally(done);
});