javascript - typescript "Cannot find name "

Question

我是 TypeScript 的新手。

我创建了一个包含一些私有(private)字段的类。当我尝试在类方法中的匿名回调函数中为其中一个字段赋值时，出现错误 ...

(TS) Cannot Find the name '_tokens'

我怀疑存在范围问题，但根据我对 JavaScript 的理解，这应该不是问题。我不确定如何修复它。有任何想法吗？

请参阅 .. "populateTokens()"错误方法。

class SingleSignOn {

    private _appTokensURL: string  = "/api/IFSessionCache/Auth/";
    private _tokens: string[];

    /**
     * Initialize an instance of the SingleSignOn class to manage the permissions for the 
     * application associated with the application.
     */
    constructor() {

        this.populateTokens();
    };


    /**
     * Gets a list of permissions tokens associated with the currently logged on user for 
     * the application.
     */
    private getApplicationTokens(): Q.IPromise<{}> {

        return Unique.AJAX.Get(this._appTokensURL, null, ENUMS.AjaxContentTypes.JSON);
    };


    private populateTokens () {

        this.getApplicationTokens().then(
            function (data) {
                _tokens = <string[]>data; // (TS) Cannot find name "_tokens"
            });
    };
};

Answer 1

你使用了错误的语法:

this.getApplicationTokens().then(
(data) => {
    this._tokens = <string[]>data; // note: turned into an arrow function and added the `this` keyword
});

注意如果您继续使用function() ... 语法，this 关键字将不指向类实例，但给 callee

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

问候