JavaScript(量角器)中函数的值返回为未定义 [英] value of a function in JavaScript(protractor) returns as undefined

问题描述

我正在使用量角器来检索文本.

im using protractor to retrieve a text.

其中一个功能是

//get the Impersonation ID
this.getUserSessionID = function(){
    //get whole text
    UserImpersonateTextElement.getText().then(function(text) {
        var tempText = text;
        var startString = 'session ID is ';
        var sessionID = tempText.substring(tempText.lastIndexOf(startString)+startString.length,tempText.length);
        console.log('sessionID is:'+sessionID);
        return sessionID;
    });
};

并且我在另一个js(我在其中导入了上述js)文件中调用了该函数

and im calling the function in another js(where i imported the above js) file

var getUserImpersonationID = ImpersonationSuccessPage.getUserSessionID();

当我尝试

console.log('User Impersonation ID is:'+getUserImpersonationID);

我得到 undefined 作为值.

i get undefined as the value.

但是函数中的console.log('sessionID is:'+sessionID);显示正确的值.

but the console.log('sessionID is:'+sessionID); in the function displays proper value.

谁能建议我在这里做错了什么?

Can anyone suggest what im doing wrong here?

推荐答案

获取文本的内部调用返回一个承诺.继续并返回该承诺，然后您可以在对 getUserSessionID 的调用中链接一个 then.示例

The internal call to get text returns a promise. Go ahead and return that promise and then you can chain a then in the call to getUserSessionID. Example

this.getUserSessionID = function(){
//get whole text
    return UserImpersonateTextElement.getText().then(function(text) {
    var tempText = text;
    var startString = 'session ID is ';
    var sessionID = tempText.substring(tempText.lastIndexOf(startString)+startString.length,tempText.length);
    console.log('sessionID is:'+sessionID);
    return sessionID;
   });
};

在通话中你会这样做:

getUserSessionID().then(function(sessionId){
  console.log('You session ID is ',sessionId);
})

或者，由于expect 假设要解决该承诺，您可以检查您是否有一个带有expect 的ID:

Or, since expect is suppose to resolve that promise you can check if you have an ID with expect:

expect(this.getUserSessionID()).not.toBeNull();

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