gulp-file-inject

Install:

npm install -D gulp-file-inject

Use:

var gulp = require('gulp');
var inject = require('gulp-file-inject');

var fs = require('fs');

function replacer(filepath, filename, callback) {
    // template to inject
    var str = "var template = '{{template}}'";
    
    // get the html file by the same name
    fs.readFile(filename.replace('.js', '.html'), function(err, file) {
        if (err) {
            return callback(err);
        }
        
        // make sure you minify the html first
        file = file.replace(/\n\r/, ' ').replace("'", '"');
        str = str.replace('{{template}}', file);
        callback(undefined, str);
    });
}

gulp.task('inject', function(){
    return gulp.src('js/*.js')
        .pipe(inject(/myregex/g, replacer))
        .pipe(gulp.dest('build/js'));
});

Notes:

More docs are soon to come, I promise.

This is heavily based on gulp-replace by lazd.