油猴（1）

<div class='post_item'>
  <div class='post_item_body'>
    <h3>
      <a href='//baidu.com'>链接</a>
    </h3>
  </div>
</div>
<div class='post_item'>
  <div class='post_item_body'>
    <h3>
      <a href='//baidu1.com'>链接</a>
    </h3>
  </div>
</div>
<div class='post_item'>
  <div class='post_item_body'>
    <h3>
      <a href='//baidu2.com'>链接</a>
    </h3>
  </div>
</div>
<div class='post_item'>
  <div class='post_item_body'>
    <h3>
      <a href='//baidu3.com'>链接</a>
    </h3>
  </div>
</div>
<div class='post_item'>
  <div class='post_item_body'>
    <h3>
      <a href='//baidu4.com'>链接</a>
    </h3>
  </div>
</div>

  // let els = $('.post_item h3 a').get()
  // // console.log(els)
  // els.forEach(item=>{
  //   console.log(item.href)
  // })

  // console.log(document.querySelector('a').tagName)
  let els = document.querySelectorAll('.post_item')
  let elArr = Array.from(els)

  let isArray = function (b) {
    return Object.prototype.toString.call(b).slice(8, -1) === 'Array'
  }

  function findHref(arrays) {
    if (isArray(arrays) && arrays.length) {
      Array.from(arrays).forEach(item => {
        if (item.tagName === 'DIV') {
          findHref(Array.from(item.children))
        } else if (item.tagName === 'H3') {
          findHref(Array.from(item.children))
        } else {
          console.log(item.href)
        }
      })
    }
  }

  findHref(elArr)

 油猴代码

// ==UserScript==
// @name         博客园首页a链接地址
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  博客园首页a链接地址
// @author       You
// @match        https://www.cnblogs.com/legacy
// @icon         https://www.google.com/s2/favicons?domain=undefined.localhost
// @require      http://code.jquery.com/jquery-migrate-1.2.1.min.js
// @grant        none
/* globals jQuery, $, waitForKeyElements */
// ==/UserScript==

(function() {
    'use strict';
    let els = $('.post_item h3 a').get()
    els.forEach(item=>{
        console.log(item.href)
    })
    // Your code here...
})();

 原生方法

  let els = document.querySelectorAll('.small-item a')
  els.forEach(item=>{
    console.log(item.href)
  })