SOURCE

$(function() {
    $("#user").change(function(){
    	var userName = $(this).val();
    	$("#input").val(userName);
    });
  $("#s1").click(function() {
    
    	var endTime = new Date().valueOf();
    	var type = $("#time").val();
    var t = 1;
    if(type = 1){
    	var startTime= new Date('2018-1-1').valueOf();
      t = 2;
    }
        if(type = 2){
    	var startTime= endTime - 1000 * 60 * 60 * 24 * 7;
    }
        if(type = 3){
    	var startTime= endTime - 1000 * 60 * 60 * 24 * 30;
    }
    
    var word = $("#input").val() || $("#user").val();
    
      var paramsStr = [{
            "key": "wd",
            "value": encodeURIComponent(word)
        }, {
            "key": "si",
            "value": "zhidao.baidu.com"
        }, {
            "key": "gpc",
            "value": `stf%3D${new Date(startTime).valueOf() / 1000 | 0}%2C${new Date(endTime).valueOf() / 1000 | 0}%7Cstftype%3D${t}`
        },
        {
            "key": "ct",
            "value": "2097152"
        }
        ].map(e => e.key + '=' + e.value).join('&');

        var result = 'https://www.baidu.com/s?' + paramsStr;
    
  
    $("#container").html(`<iframe src="${result}">`)
  });
});

时间：
<select id="time">
  <option value="1">
    2018年1月起
  </option>
  <option value="2">
    一周内
  </option>
  <option value="3">
    一月内
  </option>
</select>

<br><br>

用户：<select id="user">
  <option>
    新事称景
  </option>
  <option>
    一颗山竹的梦想
  </option>
  <option>
    吊丝小弟弟
  </option>
  <option>
    仓苍酱
  </option>
</select>
<br><br>
<input id="input" placeholder="输入要查询的用户">
<button id="s1">
  搜索用户
</button>
<br><br>
<div id="container"></div>

#str {
  width: 500px;
  height: 100px;
}

iframe {
  width: 720px;
  height: 700px;
}