Javascript：从嵌套函数调用外部方法[重复]答案

【问题标题】：Javascript: outer method calling from nested functions [duplicate]Javascript：从嵌套函数调用外部方法[重复]
【发布时间】：2019-09-19 23:06:12
【问题描述】：

我想打电话给openSnackBar，但我遇到了异常。任何人都可以请帮助我如何处理来自嵌套函数的外部方法调用？

export class DetailsComponent implements OnInit, OnDestroy
{
updateTodoPromise.then(function (fulfilled) {
            // yay, you got a new phone
            this.openSnackBar('Task saved successfully!', 'CLOSE');
        })
        .catch(function (error) {
            // ops, mom don't buy it
            console.log(error.message);
            this.openSnackBar('Task saved successfully!','CLOSE');
        });

    }

    public openSnackBar(full: string, full2: string) {
        this.snackBar.open(full, full2, {
            duration: 5000,
        });
    }

【问题讨论】：

标签： javascript typescript ecmascript-6 ecmascript-5

【解决方案1】：

使用 ES6 双箭头符号来保存 this 范围。

export class DetailsComponent implements OnInit, OnDestroy
{
updateTodoPromise.then( fulfilled => { // <--- here
            // yay, you got a new phone
            this.openSnackBar('Task saved successfully!', 'CLOSE');
        })
        .catch( error => {  // <--- and here
            // ops, mom don't buy it
            console.log(error.message);
            this.openSnackBar('Task saved successfully!','CLOSE');
        });

    }

    public openSnackBar(full: string, full2: string) {
        this.snackBar.open(full, full2, {
            duration: 5000,
        });
    }

【讨论】：