What is obfuscation in javascript

Obfuscation is the deliberate act of creating obfuscated javascript code(i.e, source or machine code) that is difficult for humans to understand. It is something similar to encryption, but a machine can understand the code and execute it. Let's see the below function before Obfuscation,

function greeting() {
console.log("Hello, welcome to JS world");
}

And after the code Obfuscation, it would be appeared as below,

eval(
(function (p, a, c, k, e, d) {
e = function (c) {
return c;
};
if (!"".replace(/^/, String)) {
while (c--) {
d[c] = k[c] || c;
}
k = [
function (e) {
return d[e];
},
];
e = function () {
return "\\w+";
};
c = 1;
}
while (c--) {
if (k[c]) {
p = p.replace(new RegExp("\\b" + e(c) + "\\b", "g"), k[c]);
}
}
return p;
})(
"2 1(){0.3('4, 7 6 5 8')}",
9,
9,
"console|greeting|function|log|Hello|JS|to|welcome|world".split("|"),
0,
{}
)
);