javascript - 如何检测退格键是否被保留

Question

我如何检测退格键是否被按下并在 js 中保持。我设置了事件监听器，但每次按下退格键时它都会触发我需要区分按下和按住吗？

HTML 输入:

(keydown)="fixIePosition($event);

TS 回调:

fixIePosition(e) {

    if ((navigator.userAgent.indexOf('Trident') !== -1 ||
        navigator.userAgent.indexOf('Edge') !== -1)
        && e.keyCode === 8) {
        const selectionStart = e.target.selectionStart;

        if (selectionStart === 3) {
            e.target.setSelectionRange(3, 3);
        // } else if (selectionStart === 5 && e.type === 'keydown') {
        //     console.log(e);
        //    // e.target.setSelectionRange(selectionStart, selectionStart);
        //     this.ieFixPosition = true;
        } else if (selectionStart === 4 && e.type === 'keyup') {
            if (this.ieFixPosition) {
                e.target.setSelectionRange(selectionStart, selectionStart);
                this.ieFixPosition = false;
            } else {
                e.target.setSelectionRange(selectionStart - 1, selectionStart - 1);
            }
        }
    }
}

Answer 1

你可以试试键盘事件repeat检测按键保持。

document.addEventListener('keydown', (event) => {
        if (event.repeat) {
            // Key Hold Event
        } else {
            // Key Press Event
        }
    });