js array for loop performance compare All In One

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js Array for loop performance


// const boxes = [...``.padStart(10, ` `)].map((item, i) => ({}));
const boxes = [...``.padStart(1, ` `)].map((item, i) => ({}));
const creative_ids_map = [...``.padStart(1000000, ` `)].map((item, i) => ({
  creative_id: i + 1,
  creative_name: `${i + 1}`,
}));
const creative_boxes = [];

const start = new Date().getTime();
console.log("once_time", start);

boxes.forEach(item => {
  const creativeIds = [];
  const creativeIdsMap = [];
  // creative_ids_map 需要 for 循环一次  (👎代码行数多，👍循环次数少)
  for (const obj of creative_ids_map) {
      const {
          creative_id,
          creative_name,
      } = obj;
      creativeIds.push(creative_id);
      creativeIdsMap.push({
          creative_id,
          creative_name,
      });
  }
  creative_boxes.push({
      creative_ids: creativeIds,
      creative_ids_map: creativeIdsMap,
  });
});

const end = new Date().getTime();
console.log("once_time", end);
console.log("once cost time", (end - start));


// const boxes = [...``.padStart(10, ` `)].map((item, i) => ({}));
const boxes = [...``.padStart(1, ` `)].map((item, i) => ({}));
const creative_ids_map = [...``.padStart(1000000, ` `)].map((item, i) => ({
  creative_id: i + 1,
  creative_name: `${i + 1}`,
}));
const creative_boxes = [];

const start = new Date().getTime();
console.log("twice_time", start);

boxes.forEach(item => {
  // creative_ids_map 需要 for 循环两次 (👍代码行数少，👎循环次数多)
  const creativeIds = creative_ids_map.map(obj => obj.creative_id) || [];
  const creativeIdsMap = creative_ids_map.map(obj => ({
    creative_id: obj.creative_id,
    creative_name: obj. creative_name,
  })) || [];
  creative_boxes.push({
      creative_ids: creativeIds,
      creative_ids_map: creativeIdsMap,
  });
});

const end = new Date().getTime();
console.log("twice_time", end);
console.log("twice cost time", (end - start));