Core JavaScript 1.5 Reference:Statements:const
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[edit] Summary
Declares a read-only, named constant.
| Statement | |
| Implemented in: | JavaScript 1.5, NES 6.0 (Netscape extension, C engine only) |
[edit] Syntax
const varname1 [= value1], varname2 [= value2], ..., varnameN [= valueN];
[edit] Parameters
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varnameN - Constant name. It can be any legal identifier.
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valueN - Value of the constant. It can be any legal expression.
[edit] Description
Creates a constant that can be global or local to the function in which it is declared. Constants follow the same scope rules as variables.
The value of a constant cannot change through re-assignment, and a constant cannot be re-declared. Because of this, although it is possible to declare a constant without initializing it, it would be useless to do so.
A constant cannot share its name with a function or a variable in the same scope.
const is a Mozilla-specific extension, it is not supported by IE, but has been supported by Opera since version 9.0.
[edit] Examples
[edit] Example: Using const
The following example produces the output "a is 7."
const a = 7;
document.writeln("a is " + a + ".");