Proxy API usage scenarios —— Enhanced Array

enhanced-array.js

function enhancedArray(arr) {
  return new Proxy(arr, {
    get(target, property, receiver) {
      const range = getRange(property);
      const indices = range ? range : getIndices(property);
      const values = indices.map((index) => {
        const key = index < 0 ? target.length + index : index;
        return Reflect.get(target, key, receiver);
      });
      return values.length === 1 ? values[0] : values;
    },
  });

  function getRange(str) {
    var [start, end] = str.split(":").map(Number);
    if (typeof end === "undefined") return false;

    let range = [];
    for (let i = start; i < end; i++) {
      range = range.concat(i);
    }
    return range;
  }

  function getIndices(str) {
    return str.split(",").map(Number);
  }
}