get

2024年04月08日

柏拉文

越努力，越幸运

一、认识

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二、实现

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2.1 Bolawen reduce

function get(object, path, defaultValue) {
  const pathRegExp = /[,\[\].]+?/;
  const keys = Array.isArray(path)
    ? path
    : path.split(pathRegExp).filter(Boolean);

  return keys.reduce((value, key) => {
    if (
      value &&
      typeof value === "object" &&
      Object.prototype.hasOwnProperty.call(value, key)
    ) {
      return value[key];
    } else {
      return defaultValue;
    }
  }, object);
}

测试代码

const object = { a: [{ b: { c: 3 } }] };

console.log(get(object, "a[0].b.c"));
console.log(get(object, ["a", "0", "b", "c"]));
console.log(get(object, "a.b.c", "default"));

2.2 Bolawen for……of

function get(object, path, defaultValue) {
  const pathRegExp = /[,\[\].]+?/;
  const keys = Array.isArray(path)
    ? path
    : path.split(pathRegExp).filter(Boolean);

  for (const key of keys) {
    if (
      object &&
      typeof object === "object" &&
      Object.hasOwnProperty.call(object, key)
    ) {
      object = object[key];
    } else {
      return defaultValue;
    }
  }

  return object;
}

测试代码

const object = { a: [{ b: { c: 3 } }] };

console.log(get(object, "a[0].b.c"));
console.log(get(object, ["a", "0", "b", "c"]));
console.log(get(object, "a.b.c", "default"));