替换 if 和 else

单一条件

const getOwner = () => {
  if (pjtName === "项目A") {
    return "张三";
  } else if (pjtName === "项目B") {
    return "李四";
  } else if (pjtName === "项目C") {
    return "王五";
  } else {
    return "小马哥";
  }
};

重构以上代码

案例一

const getOwner2 = (pjtName) => {
  const map = {
    项目A: "张三",
    项目B: "李四",
    项目C: "王五",
  };
  return map[pjtName] ? map[pjtName] : "小马哥";
};

案例二

const commodity = new Map([
  ["phone", 1999],
  ["computer", 9999],
  ["television", 2999],
  ["gameBoy", 3999],
]);

const price = (name) => {
  return commodity.get(name);
};
price("phone"); // 1999

复合条件

案例一

const getImg = (res) => {
  // 未中奖
  if (res.type === 0) {
    return "pic1";
  }
  // 现金
  if (res.type === 1 && res.count === 6.6) {
    return "pic2";
  }
  if (res.type === 1 && res.count === 6.6) {
    return "pic3";
  }
  // 会员卡
  if (res.type === 2 && res.count === 1) {
    return "pic4";
  }
  if (res.type === 2 && res.count === 3) {
    return "pic5";
  }
  if (res.type === 2 && res.count === 5) {
    return "pic6";
  }
  if (res.type === 2 && res.count === 31) {
    return "pic7";
  }
  if (res.type === 2 && res.count === 365) {
    return "pic8";
  }
  // 优惠卷
  if (res.type === 3) {
    return "pic9";
  }
};

重构

const refactoGetImg = (res) => {
  const arr = [
    [0, false, "pic1"],
    [1, 6.6, "pic2"],
    [1, 8.8, "pic3"],
    [2, 1, "pic4"],
    [2, 3, "pic5"],
    [2, 5, "pic6"],
    [2, 31, "pic7"],
    [2, 365, "pic8"],
    [3, false, "pic9"],
  ];
  return arr.filter((item) => {
    return (
      res.type === item[0] &&
      (res.count === item[1] || !!res.count === !!item[1])
    );
  })[0][2];
};

调用

console.log(refactoGetImg({ type: 0 }));
console.log(refactoGetImg({ type: 1, count: 6.6 }));
console.log(refactoGetImg({ type: 3 }));

案例二

if (this.caseSource.length > 0) {
  this.formItem.caseSource = this.caseSource.join(",");
}

if (this.penaltiesType.length > 0) {
  this.formItem.penaltiesType = this.penaltiesType.join(",");
}

if (this.administrativeStrongEnforce.length > 0) {
  this.formItem.administrativeStrongEnforce =
    this.administrativeStrongEnforce.join(",");
}

if (this.administrativeReconsideration.length > 0) {
  this.formItem.administrativeReconsideration =
    this.administrativeReconsideration.join(",");
}

if (this.administrativeLitigation.length > 0) {
  this.formItem.administrativeLitigation =
    this.administrativeLitigation.join(",");
}

重构为

let init = [
  "caseSource",
  "penaltiesType",
  "administrativeStrongEnforce",
  "administrativeReconsideration",
  "administrativeLitigation",
];
for (var i = 0; i < init.length; i++) {
  let item = init[i];
  if (this[item].length > 0) {
    this.formItem[item] = this[item].join(",");
  }
}