Interfaces often represent important software contracts, so it can be helpful to prefix their names with I
.
The unprefixed name is then available for a class that provides a standard implementation of the interface.
Alternatively, the contributor guidelines for the TypeScript repo suggest
never prefixing interfaces with I
.
This rule enforces whether or not the I
prefix is required for interface names.
The _
prefix is sometimes used to designate a private declaration, so the rule also supports a private interface
that might be named _IAnimal
instead of IAnimal
.
This rule has an object option:
{ "prefixWithI": "never" }
: (default) disallows all interfaces being prefixed with"I"
or"_I"
{ "prefixWithI": "always" }
: requires all interfaces be prefixed with"I"
(but does not allow"_I"
){ "prefixWithI": "always", "allowUnderscorePrefix": true }
: requires all interfaces be prefixed with either"I"
or"_I"
For backwards compatibility, this rule supports a string option instead:
"never"
: Equivalent to{ "prefixWithI": "never" }
"always"
: Equivalent to{ "prefixWithI": "always" }
Configuration: { "prefixWithI": "never" }
The following patterns are considered warnings:
interface IAnimal {
name: string;
}
interface IIguana {
name: string;
}
interface _IAnimal {
name: string;
}
The following patterns are not warnings:
interface Animal {
name: string;
}
interface Iguana {
name: string;
}
Configuration: { "prefixWithI": "always" }
The following patterns are considered warnings:
interface Animal {
name: string;
}
interface Iguana {
name: string;
}
interface _IAnimal {
name: string;
}
The following patterns are not warnings:
interface IAnimal {
name: string;
}
interface IIguana {
name: string;
}
Configuration: { "prefixWithI": "always", "allowUnderscorePrefix": true }
The following patterns are considered warnings:
interface Animal {
name: string;
}
interface Iguana {
name: string;
}
The following patterns are not warnings:
interface IAnimal {
name: string;
}
interface IIguana {
name: string;
}
interface _IAnimal {
name: string;
}
If you do not want to enforce interface name prefixing.
TypeScript Interfaces
TSLint: interface-name