问题：How to calculate the percentage between 3 numbers in javascript?

像这样

function calculatePercentageOf3 (firstVal, midVal, lastVal)
 {
       return (midVal - firstVal) / (lastVal - firstVal) * 100;
 }

演示

x一个一个一个一个x一个一个二个x

更新

此代码查找与某个范围内的某个百分比对应的值。

let valueStart = 120;
let valueEnd = 970;
let percentage = 29;

let value = valueStart + percentage * (valueEnd - valueStart) / 100;

console.log(value);

你可以这样做：

const start_value = 120;
const end_value = 970;

const calculate_percentage = (input_number) => {
  if(input_number < start_value) return 0;
  if(input_number > end_value) return 100;
  return (input_number-start_value)/(end_value-start_value)*100;
}

console.log(calculate_percentage(120))
console.log(calculate_percentage(500))
console.log(calculate_percentage(970))

一个数学好的人可以把三个数字变成百分之三。

var ywidth = (+100-xwidth); //var zwidth = (+100-ywidth);