flying-hero
96f6318101
新增: - backend/venv/ - Python 虚拟环境 - backend/start.sh - 启动脚本（使用虚拟环境） - backend/requirements.txt - 依赖列表 - .gitignore - 忽略虚拟环境和缓存文件 说明: - 每个项目使用独立虚拟环境 - 避免依赖冲突 - 启动脚本自动创建和激活虚拟环境
2.1 KiB
2.1 KiB
Selector Specificity
Usage
Add Selector Specificity to your project:
npm install postcss @csstools/selector-specificity --save-dev
import parser from 'postcss-selector-parser';
import { selectorSpecificity } from '@csstools/selector-specificity';
const selectorAST = parser().astSync('#foo:has(> .foo)');
const specificity = selectorSpecificity(selectorAST);
console.log(specificity.a); // 1
console.log(specificity.b); // 1
console.log(specificity.c); // 0
selectorSpecificity takes a single selector, not a list of selectors (not : a, b, c).
To compare or otherwise manipulate lists of selectors you need to call selectorSpecificity on each part.
Comparing
The package exports a utility function to compare two specificities.
import { selectorSpecificity, compare } from '@csstools/selector-specificity';
const s1 = selectorSpecificity(ast1);
const s2 = selectorSpecificity(ast2);
compare(s1, s2); // -1 | 0 | 1
- if
s1 < s2thencompare(s1, s2)returns a negative number (< 0) - if
s1 > s2thencompare(s1, s2)returns a positive number (> 0) - if
s1 === s2thencompare(s1, s2)returns zero (=== 0)
Prior Art
For CSSTools we always use postcss-selector-parser and want to calculate specificity from this AST.