BEM style string
题目
The Block, Element, Modifier methodology (BEM) is a popular naming convention for classes in CSS.
For example, the block component would be represented as btn
, element that depends upon the block would be represented as btn__price
, modifier that changes the style of the block would be represented as btn--big
or btn__price--warning
.
Implement BEM<B, E, M>
which generate string union from these three parameters. Where B
is a string literal, E
and M
are string arrays (can be empty).
解答
ts
type BEM<
B extends string,
E extends string[],
M extends string[]
> = `${B}${E extends [] ? "" : `__${E[number]}`}${M extends []
? ""
: `--${M[number]}`}`;