JS利用正則表達式替換字符串中的內容

  //從字符串'Is this a cat is'中剪去'is':
  var str='Is this a cat is';

  var subStr=new RegExp('is');//創建正則表達式對象
  var result=str.replace(subStr,"");//把'is'替換為空字符串
  console.log(result);//Is th a cat 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'替換為空字符串
  console.log(result);//this a cat 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'替換為空字符串
  console.log(result);//th a cat

  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'替換為空字符串
  console.log(result);//th a cat

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