Check if file contains a specific string in GULP - gulp

Question

I am attempting to use GULP4 to compress a series of HTML and PHP files. A problem I am running into is some of the files contain a <pre> tag. I do not want to compress those files because it would mess up that file. Is there a way using GULP I can evaluate if a file contains the string <pre> and if it does, avoid running compression on that file?
Here is my relevant code:
const gulp = require('gulp');
const {src, series, parallel, dest} = require('gulp');
const GulpReplace = require('gulp-replace');
function no_2_spaces_purchasingdemand_php()
{
console.log("no 2 spaces purchasingdemand_php")
return gulp.src
(
'dist/purchasingdemand/**/*.php'
, { base: "./" }
)
.pipe
(
GulpReplace(' ','☺☻')
)
.pipe
(
GulpReplace('☻☺','')
)
.pipe
(
GulpReplace('☺☻',' ')
)
.pipe(gulp.dest('./'))
}
exports.default = series(no_2_spaces_purchasingdemand_html)

Answer 1

I don't know what you are using to compress files, but here is a general example:
const gulp = require('gulp');
const filter = require('gulp-filter');
const minify = require('gulp-htmlmin');
gulp.task("preFilterTask", function () {
// return true if want the file in the stream
const preFilter = filter(function (file) {
let contents = file.contents.toString();
return !contents.match('<pre>');
});
return gulp.src("./*.html")
.pipe(preFilter)
.pipe(minify({ collapseWhitespace: true }))
.pipe(gulp.dest('filtered'));
});
gulp.task('default', gulp.series('preFilterTask'));
gulp-htmlmin by itself - for html files only - will not minify the <pre>...</pre> portion of an html file. So if you use gulp-htmlmin for html minification, you don't need to filter out those with <pre> tags.
I still showed how to filter based on file content using the gulp-filter plugin. It can access each file's contents. Return false from the filter function if you do not want that file to pass to the next pipe.