Javascript：从嵌套函数调用外部方法

我想调用

openSnackBar

，但出现异常。任何人都可以帮助我如何处理嵌套函数的外部方法调用吗

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,
        });
    }

---

使用ES6双箭头表示法保留

此

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,
        });
    }

导出类详细信息组件实现OnInit、OnDestroy
{
updateTodoPromise.then（completed=>{/{/使用ES6双箭头表示法来保留
这个
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,
        });
    }

导出类详细信息组件实现OnInit、OnDestroy
{
然后（完成=>{/{//