Code/FP/oneImpureFunc.js

//HTML结构
/**
<ul>
  <li>1</li>
  <li>2</li>
  <li>3</li>
  <li>4</li>
  <li>5</li>
  <li>6</li>
  <li>7</li>
  <li>8</li>
  <li>9</li>
</ul>
*/

//只有一个非纯函数
function batch (fn) {
  return function (target, ...args) {
    if(target.length >= 0){
      return Array.from(target).map(item => fn.apply(this, [item, ...args]));
      } else {
        return fn.apply(this, [target, ...args]);
      }
    }
}
  
function setColor (el, color) {
  el.style.color = color;
}
  
let setColors = batch(setColor);
  
let items1 = document.querySelectorAll('ul > li:nth-child(2n + 1)');
let items2 = document.querySelectorAll('ul > li:nth-child(3n + 1)');
  
setColors(items2, 'green');
setColors(items1, 'red');