(5) JavaScript Study Notes-Variables

I. Variable type 1. JS is non-type, that is, JS variables can store any type of value; 2. so when necessary, JS can quickly and automatically convert one type of value to another type; 2. Variable Declaration [javascript] // declare a single variable vara; // declare multiple variables... syntaxHighlighter. all ();

I. Variable type

1. JS is non-type, that is, JS variables can store any type of value;

2. When necessary, JS can quickly and automatically convert one type of value to another type;

2. Variable Declaration

[Javascript]
// Declare a single variable
Var;
 
// Declare multiple variables
Var a, B, sum;
 
// Declare and initialize binding
Var msg = "hello ";
Var I = 0, j = 0, k = 0;
 
// Var can also be part of the for Loop
For (var I = 0; I ++; I <10) document. write (I ,"
");

It is legal to declare the same variable multiple times, except that the value is re-assigned.

Iii. Scope of Variables

1. Local variables defined in the function have a higher priority than global variables;

2. Although var can be used in the global scope, you must use var to declare local variables.

4. undefined variables and unassigned variables www.2cto.com

1. assign values to undeclared variables without causing errors. The program will be declared implicitly in the global scope;

2. the unassigned variable has been declared. The read value is undefined.

By: dxh_0829