데이터베이스 인덱스

<div class="demo"><div class="head"><b>INDEX SEEK</b><span>WHERE id = 42</span></div><div class="tree"><div class="level"><div class="node" id="root">50</div></div><div class="branches">↙ <span>↘</span></div><div class="level"><div class="node" id="left">20 | 40</div><div class="node" id="right">60 | 80</div></div><div class="branches">↙ <span>↘</span></div><div class="level"><div class="node" id="leaf">41 · <b>42</b> · 45</div><div class="node" id="other">61 · 72 · 84</div></div></div><div class="foot"><span id="step">compare at root</span><span>tap to step</span></div></div>

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const path=['root','left','leaf'],labels=['compare 42 < 50','follow 20 | 40','found row 42'];let step=0;function advance(){document.querySelectorAll('.node').forEach(el=>el.classList.remove('on'));path.slice(0,step+1).forEach(id=>document.getElementById(id).classList.add('on'));document.getElementById('step').textContent=labels[step];step=(step+1)%3}advance();const timer=setInterval(advance,700);document.querySelector('.demo').addEventListener('pointerdown',()=>{clearInterval(timer);advance()})