Warning
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The gulp-sourcemap plugin can be removed. Gulp already has built-in support for source maps. https://gulpjs.com/docs/en/api/src/#sourcemaps

Source map support for Gulp.js.
Write inline source maps.
Inline source maps are embedded in the source file.

Example:

var gulp = require('gulp');
var sourcemaps = require('gulp-sourcemap');
gulp.src('dist/JSLite.js')
    .pipe(sourcemap({
        outSourceMap:'JSLite.js.map',
        sourceRoot:"http://jslite.io",
        write:'./build/'
    }))
    .pipe(gulp.dest('./build/'));

sourceRoot root: the sourceRoot property (see the spec)
outSourceMap The inSourceMap is only used if you also request outSourceMap (it makes no sense otherwise).