查看“︁MediaWiki:Gadget-SelectionCounter.js”︁的源代码

/* ================================================================
   MediaWiki Gadget: SelectionCounter
   功能：
   - 选中文本时显示字数统计
   - 与 RightToolbar 风格一致
   ================================================================= */

mw.loader.using(['mediawiki.util']).then(function () {
    var $counter = $('#mw-selection-counter');

    if (!$counter.length) {
        $counter = $('<div id="mw-selection-counter" class="mw-selection-counter" role="status" aria-live="polite"></div>')
            .hide()
            .appendTo('body');
    }

    var rafId = null;

    function updateCounter() {
        rafId = null;
        var active = document.activeElement;
        if (active && (active.tagName === 'INPUT' || active.tagName === 'TEXTAREA' || active.isContentEditable)) {
            $counter.hide();
            return;
        }

        var text = String(window.getSelection() || '').trim();
        if (!text) {
            $counter.hide();
            return;
        }

        var count = Array.from(text).length;
        $counter.text('已选 ' + count + ' 字').show();
    }

    document.addEventListener('selectionchange', function () {
        if (rafId) {
            return;
        }
        rafId = window.requestAnimationFrame(updateCounter);
    });
});