Why isBefore method doesn't work as expected in dayjs?

Question

I am trying to create a calendar with dayjs but doesn't work though the same code is working in momentjs.

My code is:

import dayjs from 'dayjs';


const calendar = [];
    const today = dayjs();
    const startDay = today.clone().startOf('month').startOf('week');
    const endDay = today.clone().endOf('month').endOf('week');
    
    let day = startDay.clone().subtract(1, 'day');
    
    while (day.isBefore(endDay, 'day')) {
        calendar.push(
            Array(7)
            .fill(0)
            .map(() => day.add(1, 'day').clone() )
        )
    };

After running the code, it behaves like continuous loop and shows this error:

<--- Last few GCs --->

[9148:000002DE6245A350] 188279 ms: Scavenge (reduce) 1987.6 (1992.3) -> 1986.8 (1993.3) MB, 5.3 / 0.0 ms (average mu = 0.253, current mu = 0.221) allocation failure
[9148:000002DE6245A350] 188284 ms: Scavenge (reduce) 1987.7 (1992.3) -> 1987.0 (1993.5) MB, 3.3 / 0.0 ms (average mu = 0.253, current mu = 0.221) allocation failure
[9148:000002DE6245A350] 188323 ms: Scavenge (reduce) 1987.8 (1992.5) -> 1987.0 (1993.8) MB, 5.3 / 0.0 ms (average mu = 0.253, current mu = 0.221) allocation failure

<--- JS stacktrace --->

FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory
1: 00007FF742FB481F napi_wrap+110783
2: 00007FF742F57F26 v8::base::CPU::has_sse+61862
3: 00007FF742F58E26 node::OnFatalError+294
4: 00007FF7438323BE v8::Isolate::ReportExternalAllocationLimitReached+94
5: 00007FF74381718D v8::SharedArrayBuffer::Externalize+781
6: 00007FF7436C02CC v8::internal::Heap::EphemeronKeyWriteBarrierFromCode+1516
7: 00007FF7436CB6EA v8::internal::Heap::ProtectUnprotectedMemoryChunks+1258
8: 00007FF7436C8829 v8::internal::Heap::PageFlagsAreConsistent+2457
9: 00007FF7436BD3D1 v8::internal::Heap::CollectGarbage+2049
10: 00007FF7436BB5D5 v8::internal::Heap::AllocateExternalBackingStore+1349
11: 00007FF7436DBA3B v8::internal::Factory::NewFillerObject+203
12: 00007FF74340A0B1 v8::internal::interpreter::JumpTableTargetOffsets::iterator::operator=+1409
13: 00007FF7438BB27D v8::internal::SetupIsolateDelegate::SetupHeap+465325
14: 000001673571CCAD

If I use the same code in momentjs, There is no issue and work well

What's the problem with dayjs that it doesn't working???

Answer 1

Had you try to log the day value inside the while?

put an day = day.add(1, 'day'); at the end of cicle

const calendar = [];
const today = dayjs();
const startDay = today.clone().startOf('month').startOf('week');
const endDay = today.clone().endOf('month').endOf('week');

let day = startDay.clone().subtract(1, 'day');

while (day.isBefore(endDay, 'day')) {

    console.log(day)
    calendar.push(
        Array(7)
        .fill(0)
        .map(() => day.add(1, 'day').clone() )
    )

    day = day.add(1, 'day');
};

console.log(calendar)

<script src="https://cdnjs.cloudflare.com/ajax/libs/dayjs/1.10.6/dayjs.min.js"></script>