javascript unset variable

1. What is the definition of a variable? How do I check that a variable is defined? How do I delete a variable? How do I detect if a variable is set? $ defines whether the isset ()//check variable is setDefined ()//Detect constants are setUnset

This article mainly introduces PHP Session control: Session and Cookie Details. This article describes Session and Cookie related knowledge in PHP in detail and covers a wide range of topics, for more information about PHP session control, see the

JavaScript + PHP application 1: the dynamic implementation of the double drop-down menu in the web page production --- from the Internet in the web page production, this situation is often encountered, through the selection of the main drop-down

Menu | news | web | dropdown javascript+php Application One: Dynamic implementation of double Pull-down menu in Web page making ---excerpted from the Internet In the Web page production, often encountered this situation, through the main Drop-down

javascript+php Application One: The dynamic realization of double drop-down menu in Web page making ---excerpted from the Internet In the Web page production, often encountered this situation, through the main drop-down menu selection, the dynamic

The delete operator deletes an attribute from an object or an element from an array. Today, when reading prototype code, we found the delete operator. The Code is as follows: Unset: function (key ){Var value = this. _ object [key];Delete this. _

Important knowledge points of PHP object-oriented (2 ). 1. _ toString: when an object is printed, if this method is defined by this class, the return value of this method is printed; otherwise, the result is printed based on the default PHP behavior.

1. _ toString: when an object is printed, if this method is defined by this class, the return value of this method is printed; otherwise, the result is printed based on the default PHP behavior. This method is similar to toString () in Java (). Copy

PHP programming considerations. 1. php implicit ternary operators (? :) Priority problem: Example 1: $ person $ whoor $ personlaruence; is actually equivalent to: $ personemptyempty ($ who )? Laruence: $ who; example 2 $ arr 1. hidden ternary

Summary of PHP-based programming considerations. 1. php implicit ternary operators (? :) Priority problem: Example 1: Copy the code as follows: $ person $ whoor $ personlaruence; is actually equivalent to: $ personempty ($ who )? La 1. php implicit