javascript - 范围输入逐渐改变颜色

我有一个范围输入，背景当前为静态蓝色。

我希望背景在开始时是红色的，当我向右移动时，背景逐渐变成黄色，然后变成绿色。

我怎样才能做到这一点？

这是我到目前为止所拥有的：

http://jsfiddle.net/sQx4H/386/

input[type=range] {
  -webkit-appearance: none;
  width: 200px;
  margin: 13.8px 0;
}

input[type=range]:focus {
  outline: none;
}

input[type=range]::-webkit-slider-runnable-track {
  width: 100%;
  height: 8.4px;
  cursor: pointer;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  background: #3071a9;
  border-radius: 1.3px;
  border: 0.2px solid #010101;
}

input[type=range]::-webkit-slider-thumb {
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border: 1px solid #000000;
  height: 36px;
  width: 16px;
  border-radius: 3px;
  background: #ffffff;
  cursor: pointer;
  -webkit-appearance: none;
  margin-top: -14px;
}

input[type=range]:focus::-webkit-slider-runnable-track {
  background: #367ebd;
}

input[type=range]::-moz-range-track {
  width: 100%;
  height: 8.4px;
  cursor: pointer;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  background: #3071a9;
  border-radius: 1.3px;
  border: 0.2px solid #010101;
}

input[type=range]::-moz-range-thumb {
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border: 1px solid #000000;
  height: 36px;
  width: 16px;
  border-radius: 3px;
  background: #ffffff;
  cursor: pointer;
}

input[type=range]::-ms-track {
  width: 100%;
  height: 8.4px;
  cursor: pointer;
  background: transparent;
  border-color: transparent;
  color: transparent;
}

input[type=range]::-ms-fill-lower {
  background: #2a6495;
  border: 0.2px solid #010101;
  border-radius: 2.6px;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
}

input[type=range]::-ms-fill-upper {
  background: #3071a9;
  border: 0.2px solid #010101;
  border-radius: 2.6px;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
}

input[type=range]::-ms-thumb {
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border: 1px solid #000000;
  height: 36px;
  width: 16px;
  border-radius: 3px;
  background: #ffffff;
  cursor: pointer;
  height: 8.4px;
}

input[type=range]:focus::-ms-fill-lower {
  background: #3071a9;
}

input[type=range]:focus::-ms-fill-upper {
  background: #367ebd;
}

<table>
  <tr>
    <td colspan="3">
      <input type="range" name="rangeInput" value="0" min="0" max="100">
    </td>
  </tr>
  <tr>
    <td style="text-align:left">red</td>
    <td style="text-align:center">yellow</td>
    <td style="text-align:right">green</td>
  </tr>
</table>

感谢您的帮助！ :)

最佳答案

如果您更改了一些CSS，则可以这样完成：

window.onload = function() {
  document.getElementById("my-range").addEventListener("input", function(e) {
    const ratio = 255/100;
    const currentValue = e.target.value;

    let colorMaker = [0, 0 ,0];

    if (currentValue < 50) {
       colorMaker[0] = 255;
       colorMaker[1] = currentValue * 2 * ratio;
    } else {
       colorMaker[0] = (100 - currentValue) * 2 * ratio;
       colorMaker[1] = 255
    }
    const newColor = "#" + colorMaker.map(v => Math.ceil(v).toString(16).padStart(2, "0")).join("");
    e.target.style.backgroundColor = newColor;
  });
}

input[type=range] {
  -webkit-appearance: none;
  width: 200px;
  margin: 13.8px 0;
  background-color: red;
}
input[type=range]:focus {
  outline: none;
}
input[type=range]::-webkit-slider-runnable-track {
  width: 100%;
  height: 8.4px;
  cursor: pointer;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;

  border-radius: 1.3px;
  border: 0.2px solid #010101;
}
input[type=range]::-webkit-slider-thumb {
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border: 1px solid #000000;
  height: 36px;
  width: 16px;
  border-radius: 3px;
  background: #ffffff;
  cursor: pointer;
  -webkit-appearance: none;
  margin-top: -14px;
}

input[type=range]::-moz-range-track {
  width: 100%;
  height: 8.4px;
  cursor: pointer;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border-radius: 1.3px;
  border: 0.2px solid #010101;
}
input[type=range]::-moz-range-thumb {
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border: 1px solid #000000;
  height: 36px;
  width: 16px;
  border-radius: 3px;
  background: #ffffff;
  cursor: pointer;
}
input[type=range]::-ms-track {
  width: 100%;
  height: 8.4px;
  cursor: pointer;
  background: transparent;
  border-color: transparent;
  color: transparent;
}
input[type=range]::-ms-fill-lower {
  background: #2a6495;
  border: 0.2px solid #010101;
  border-radius: 2.6px;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
}
input[type=range]::-ms-fill-upper {
  background: #3071a9;
  border: 0.2px solid #010101;
  border-radius: 2.6px;
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
}
input[type=range]::-ms-thumb {
  box-shadow: 1px 1px 1px #000000, 0px 0px 1px #0d0d0d;
  border: 1px solid #000000;
  height: 36px;
  width: 16px;
  border-radius: 3px;
  background: #ffffff;
  cursor: pointer;
  height: 8.4px;
}
input[type=range]:focus::-ms-fill-lower {
  background: #3071a9;
}
input[type=range]:focus::-ms-fill-upper {
  background: #367ebd;
}

<table>
<tr>
  <td colspan="3">
    <input id="my-range" type="range" name="rangeInput" value="0" min="0" max="100">
  </td>
</tr>
<tr>
  <td style="text-align:left">red</td>
  <td style="text-align:center">yellow</td>
  <td style="text-align:right">green</td>
</tr>
</table>