JavaScript Explore--3

typeof and Instanceof

• The string type can be judged by typeof, but when the array, object, regular, null are returned, it is all object, so instanceof can be used to determine the type

  <script>var str = ‘Lee‘;alert(typeof str);//stringvar arr = [1,2,3];alert(typeof arr);//objectalert(arr instanceof Array);//true</script>

• Note: When the type is string, it will be false if you judge with instanceof

  <script>var str = ‘xu xiao dai‘;alert(str instanceof String);//falsevar strObj = new String(‘xu xiao dai‘);alert(strObj instanceof String);//true</script>

JavaScript Explore--3