#### 改造postcss-px-to-viewport

##### 增加exclude配置项
配置文件.postcssrc.js（修改第三方库被影响的情况）
``
"postcss-px-to-viewport": {
viewportWidth: 750,
viewportHeight: 1334,
unitPrecision: 3,
viewportUnit: 'vw',
selectorBlackList: ['.ignore', '.hairlines'],
minPixelValue: 1,
mediaQuery: false,
exclude: /(\/|\\)(node_modules)(\/|\\)/
},
`

postcss-px-to-viewport ![NPM version](http://badge.fury.io/js/postcss-px-to-viewport)

A plugin for PostCSS that generates viewport units (vw, vh, vmin, vmax) from pixel units.

Usage

If your project involves a fixed width, this script will help to convert pixels into viewport units.

$3

`css
// input

.class {
margin: -10px .5vh;
padding: 5vmin 9.5px 1px;
border: 3px solid black;
border-bottom-width: 1px;
font-size: 14px;
line-height: 20px;
}

.class2 {
border: 1px solid black;
margin-bottom: 1px;
font-size: 20px;
line-height: 30px;
}

@media (min-width: 750px) {
.class3 {
font-size: 16px;
line-height: 22px;
}
}

// output

.class {
margin: -3.125vw .5vh;
padding: 5vmin 2.96875vw 1px;
border: 0.9375vw solid black;
border-bottom-width: 1px;
font-size: 4.375vw;
line-height: 6.25vw;
}

.class2 {
border: 1px solid black;
margin-bottom: 1px;
font-size: 6.25vw;
line-height: 9.375vw;
}

@media (min-width: 234.375vw) {
.class3 {
font-size: 5vw;
line-height: 6.875vw;
}
}
`

$3

`js
'use strict';

var fs = require('fs');
var postcss = require('postcss');
var pxToViewport = require('..');
var css = fs.readFileSync('main.css', 'utf8');
var options = {
replace: false
};
var processedCss = postcss(pxToViewport(options)).process(css).css;

fs.writeFile('main-viewport.css', processedCss, function (err) {
if (err) {
throw err;
}
console.log('File with viewport units written.');
});
`

$3

Default:
`js
{
viewportWidth: 320,
viewportHeight: 568,
unitPrecision: 5,
viewportUnit: 'vw',
selectorBlackList: [],
minPixelValue: 1,
mediaQuery: false
}
`
- viewportWidth (Number) The width of the viewport.
- viewportHeight (Number) The height of the viewport.
- unitPrecision (Number) The decimal numbers to allow the REM units to grow to.
- viewportUnit (String) Expected units.
- selectorBlackList (Array) The selectors to ignore and leave as px.
- If value is string, it checks to see if selector contains the string.
- ['body'] will match .body-class
- If value is regexp, it checks to see if the selector matches the regexp.
- [/^body$/] will match body but not .body
- minPixelValue (Number) Set the minimum pixel value to replace.
- mediaQuery (Boolean) Allow px to be converted in media queries.

$3

`js
var gulp = require('gulp');
var postcss = require('gulp-postcss');
var pxtoviewport = require('postcss-px-to-viewport');

gulp.task('css', function () {

var processors = [
pxtoviewport({
viewportWidth: 320,
viewportUnit: 'vmin'
})
];

return gulp.src(['build/css/*/.css'])
.pipe(postcss(processors))
.pipe(gulp.dest('build/css'));
});
``