let keyword always show not defined error in typescript

Question

I have below part of code:

if (this.holdReasonList.length == 1 || this.holdReasonList == undefined || this.holdReasonList.length == 0) {
            return this._cciDataService.getHoldReasonDropList()
                .pipe(takeUntil(this.unsubscribe))
                .subscribe((res) => {
                    if (res.Success) {
                        let defaultList = [];
                        res.Data.forEach((reason: string) => {
                            defaultList.push(reason.trim());
                        })

I always got undefined error of defaultList after I called this line:

let defaultList = [];

I do not understand why defaultList is not defined since I clearly declared it.

Thanks for the help in advance!

UPDATE:

Thanks for the advice! Since I tried put the let defaultList=[] outiside the whole piece of the subscribe block, it works now.

But the reason is not clear. I set the break point and type let defaultList = [] in the console and it also returns undefined. Please see below screenshot:

I think I do not need to even think of where the defaultList to be used, the defualtList is undefined right after the declaration. I do not have any chance to even use its value....

Answer 1

Ok. When I debug on Chrome devTool, the variable is defined....The issue was that I was debugging by using VSCode.

Be aware that let keyword will cause undefined variable on VSCode debugger.