JS利用正則表達式替換字元串中的內容

//從字元串'Is this all there is'中剪去'is':
  var str='Is this all there is';

  var subStr=new RegExp('is');//創建正則表達式對象
  var result=str.replace(subStr,"");//把'is'替換為空字元串
  console.log(result);//Is th all there is

  var subStr=new RegExp('is','i');//創建正則表達式對象,不區分大小寫
  var result=str.replace(subStr,"");//把'is'替換為空字元串
  console.log(result);//this all there is
    
  var subStr=new RegExp('is','ig');//創建正則表達式對象,不區分大小寫,全局查找
  var result=str.replace(subStr,"");//把'is'替換為空字元串
  console.log(result);//th all there 

  var subStr=/is/ig;//直接量法創建正則表達式對象,不區分大小寫,全局查找
  var result=str.replace(subStr,"");//把'is'替換為空字元串
  console.log(result);//th all there 

  console.log(str);//Is this all there is 可見replace並不改變原始str