JSFiddle - React, Tailwind, and code Playground

HTML

<div id="out">

</div>

JavaScript

var input = prompt("enter your text: ","I am a sentance");
var in2 = input.split(" ");
//alert(in2.join());
var in3 = [];
var copy = [];
for (var i = 0; i < in2.length; i++) {
var curr = in2[i].split("");
in3.push(curr);
copy.push(curr);
}

var out = document.getElementById("out");
//out.innerHTML = JSON.stringify(in3);

var out2 = [];
for (var i = 0; i < in3.length; i++) {
var curr = in3[i];
var curr2 = copy[i];
var m = "";
var l1 = curr[0];
var l2 = curr[curr.length - 1];
if (curr.length >= 4){
curr2.splice(0,1);
curr2.splice(curr2.length - 1,1);
while(curr2.length > 0) {
var r = Math.floor(Math.random() * curr2.length);
m += curr2[r];
curr2.splice(r,1);
}
m = l1 + m + l2;
} else {
m = curr.join("");
}
out2.push(m);
}

out.innerHTML = out2.join(" ");