javascript - 如何在该类的另一个函数中使用在 Typescript 类中声明的函数？

Question

我有这个代码:

class ExamPage {

  tabClear() {
    page.clear(this.examName);
    page.clear(this.examVersionId);
  }

  createNew() {
    describe('Create new' , function() {
      it('Clear input boxes', function() {
        tabClear(); // <<< not recognized 
      });
    });
  }

}

谁能告诉我。我想调用函数 tabClear() 但我无法访问它。谁能告诉我该怎么做

Answer 1

如果我们需要调用我们自己类的函数，我们总是必须使用this

class ExamPage {

  tabClear() {
    page.clear(this.examName);
    page.clear(this.examVersionId);
  }

  createNew() {
    describe('Create new' , function() { 
      it('Clear input boxes', function() {
        this.tabClear(); // HERE the this.tabClear() is the answer
      });
    });
  }    
}

但实际上，我们也应该使用箭头函数表示法，这将保持 this 的正确作用域:

createNew() {
    // the function () is replaced with arrow function
    describe('Create new' , () => {
      it('Clear input boxes', () => {
        this.tabClear(); // HERE the this.tabClear() is the answer
      });
    });
  } 

在此处查看有关箭头函数的更多详细信息:

• TypeScript Arrow Function Tutorial

小引用:

“Arrow function expressions are a compact form of function expressions that omit the function keyword and have lexical scoping of this.” Basically the Arrow Function helps you retain a certain scope automatically. If you look at the outputted code from the compiler, it just creates a var _this = this; and it is used inside the function.