Create custom Decryption for Hash in 30 Minutes

function stringToArray(string){
if(typeof string == 'string'){
s = [];
for(i = 0; i < string.length; i++){
s.push(string.codePointAt(i));
}
string = s;

}
return string;
}
function easyHash(string){
string = stringToArray(string);
enc = 1;
for(k = 0; k < string.length; k++){
enc += parseFloat((string[k]+(((k*0.5)+(string[k]*10)))+"."+(string[k]+k+(k/1.3))));
}
return enc + "@" + string.length;
}

Decode Output of EasyHash('STRING')
Into Original Inputted String.

Must be done in 30 minutes.