Try the following: Create index.js with the following content in the same folder:
var bitcoin = {
base58: require('bs58'),
bitcoin: require('bitcoinjs-lib'),
ecurve: require('ecurve'),
BigInteger: require('bigi'),
Buffer: require('buffer'),
elliptic: require('elliptic'),
bs58check: require('bs58check'),
}
module.exports = bitcoin;
Then run:
browserify index.js -s bitcoin | uglifyjs > bitcoinjs.min.js