效果

千山鸟飞绝 - from hill to hill no bird in flight

html

<section class="s12-wrap">
  <p style="font-size: 12px; margin: 0;padding-right: 10px;">
    千山鸟飞绝 - from hill to hill no bird in flight
  </p>
  <svg id="size-svg" width="205.515625" height="14">
    <text
        id="size-text"
        dominant-baseline="baseline"
        font-size="12"
        y="12"
        style="line-height: 1; vertical-align: middle;"
    >
      千山鸟飞绝 - from hill to hill no bird in flight
    </text>
  </svg>
</section>

js

const svg = document.getElementById('size-svg');
const sText = document.getElementById('size-text');
const inp = document.getElementById('s12-inp');
let size = 12;
const fontsizeHeightMap = {
  1: 1.22,
  2: 2.52,
  3: 3.63,
  4: 5.02,
  5: 6.03,
  6: 7.52,
  7: 8.52,
  8: 9.14,
  9: 10.52,
  10: 11.52,
  11: 13.02,
  12: 14
};

const changeAttr = size => {
  const value = fontsizeHeightMap[size];
  svg.setAttribute('height', value);
  if (size < 3) {
    sText.setAttribute('y', value)
  } else if (size === 3) {
    sText.setAttribute('y', (value - 1).toFixed(2))
  } else {
    sText.setAttribute('y', (value - 2).toFixed(2))
  }
  sText.setAttribute('font-size', size)
  inp.value = size;
}

inp.addEventListener('change', e => {
  const num = e.target.value * 1
  console.log(num);
  if (num > 12) size = 12;
  else if (num < 0) size = 1;
  else size = num
  changeAttr(size);
})