Function onDocumentSelectionChange

packages/input-otp/src/input.tsx:101–163

()

        input.selectionDirection,
      ]
      function onDocumentSelectionChange() {
        if (document.activeElement !== input) {
          setMirrorSelectionStart(null)
          setMirrorSelectionEnd(null)
          return
        }

        // Aliases
        const _s = input.selectionStart
        const _e = input.selectionEnd
        const _dir = input.selectionDirection
        const _ml = input.maxLength
        const _val = input.value
        const _prev = inputMetadataRef.current.prev

        // Algorithm
        let start = -1
        let end = -1
        let direction: 'forward' | 'backward' | 'none' = undefined
        if (_val.length !== 0 && _s !== null && _e !== null) {
          const isSingleCaret = _s === _e
          const isInsertMode = _s === _val.length && _val.length < _ml

          if (isSingleCaret && !isInsertMode) {
            const c = _s
            if (c === 0) {
              start = 0
              end = 1
              direction = 'forward'
            } else if (c === _ml) {
              start = c - 1
              end = c
              direction = 'backward'
            } else if (_ml > 1 && _val.length > 1) {
              let offset = 0
              if (_prev[0] !== null && _prev[1] !== null) {
                direction = c < _prev[1] ? 'backward' : 'forward'
                const wasPreviouslyInserting =
                  _prev[0] === _prev[1] && _prev[0] < _ml
                if (direction === 'backward' && !wasPreviouslyInserting) {
                  offset = -1
                }
              }

              start = offset + c
              end = offset + c + 1
            }
          }

          if (start !== -1 && end !== -1 && start !== end) {
            inputRef.current.setSelectionRange(start, end, direction)
          }
        }

        // Finally, update the state
        const s = start !== -1 ? start : _s
        const e = end !== -1 ? end : _e
        const dir = direction ?? _dir