Basic knowledge of the if condition clause in the basic Javascript tutorial

This article mainly introduces the if condition statement in the basic Javascript tutorial. if is a common syntax, you can refer to it as follows:

If (coditon) statement1 (else statement2)

Coditon can be any expression, or even a Boolean value, because JavaScript will automatically convert it to a Boolean value.

If the condition execution result is true, statement1 is executed. if the condition is false, statment2 is executed. (if statement2 exists, else is not required)

Each condition statement can be a single line of code or a code block. The following is a simple example.

The code is as follows:

Var iNumber = Number (prompt ("enter a Number between 5 and 100 "));
If (isNaN (iNumber ))
Document. write ("Are you sure you entered the number. ");
Else if (iNumber> 100 | iNumber <5)
Document. write ("The value you entered is out of the range ");
Else
Document. write ("The value you entered is" + iNumber );