Binding

{{GlossarySidebar}} 

In programming, a binding is an association of an {{glossary("identifier")}}  with a value. Not all bindings are {{glossary("variable", "variables")}}  — for example, function {{glossary("parameter", "parameters")}}  and the binding created by the {{jsxref("Statements/try...catch", "catch (e)")}}  block are not “variables” in the strict sense. In addition, some bindings are implicitly created by the language — for example, {{jsxref("Operators/this", "this")}}  and new.target in JavaScript.

A binding is {{glossary("mutable")}}  if it can be re-assigned, and {{glossary("immutable")}}  otherwise; this does not mean that the value it holds is immutable.

A binding is often associated with a {{glossary("scope")}} . Some languages allow re-creating bindings (also called redeclaring) within the same scope, while others don’t; in JavaScript, whether bindings can be redeclared depends on the construct used to create the binding.

See also

• {{jsxref("Statements/var", "var")}} 
• {{jsxref("Statements/let", "let")}} 
• {{jsxref("Statements/const", "const")}} 
• {{jsxref("Statements/function", "function")}} 
• {{jsxref("Statements/class", "class")}}