JS in the delete operation

varA={x:1,y:2,z:3}; varb=[1,2,3]; Deletea.x; DeleteB[0]; $("P"). Text (1inchb); Alert (0inchb);//the element with the false corner labeled 0 has been deleted.Alert ("X"incha);//false x has been deletedConsole.log (typeof(a.x));//undefinedConsole.log (typeof(A.Y));// Numberalert (b.length);//3 The element with the corner labeled 0 is deleted, but the length of the B array is unchangedAlertDeletea);//false because variable delete declared with Var cannot be deleted

The delete operator cannot delete variables declared with Var and function

JS Hollow Statement representation

;

In some cases, an empty statement is useful, such as when a for loop does not require a loop body:

 for /* Empty */; // for loop empty statement, the C array is re-assigned Console.log (c[1]); // >>1

If there is no ";", the next statement of the For loop is iterated