Nodejs String from Ascii85 fromAscii85()

Method Source Code

String.prototype.fromAscii85 = function() {
    console.log(this)//from w w w  . jav a 2  s. c  o  m
    let pad = 'u', addnum = 0, s = this.substring(2, this.length - 2).replace(/\s/g, ''), str = '', res = '';
    for (let i = 0; i < s.length; i++)
        str += s[i] === 'z' ? '!!!!!' : s[i];
    while (str.length % 5 !== 0)
    {
        str += pad;
        addnum ++;
    }
    for (let i = 0; i < str.length; i += 5)
    {
        let temp = str.substr(i, 5), decode = [], sum = 0, sum2str = '';
        for (let j = 0; j < 5; j++)
        {
            let t = temp[j].charCodeAt() - 33;
            decode.push(t);
        }
        for (let i = 4; i >= 0; i--)
            sum += decode[i] * Math.pow(85, 4 - i);
        sum2str = sum.toString(2);
        while (sum2str.length % 32 !== 0)
            sum2str = '0' + sum2str;
        for (let i = 0; i < sum2str.length; i += 8)
        {
            let temp = parseInt(sum2str.substr(i, 8), 2);
            res += String.fromCharCode(temp);
        }
    }
    res = res.substr(0, res.length - addnum);
    return res;
};

Related

1. fromAscii85()

   String.prototype.fromAscii85 = function() {
     var str = this.slice(2, -2).replace(/\s/g, ''), result = ''
     while (str.length) {
       if (str[0] == 'z') {
         result += '\u0000\u0000\u0000\u0000'
         str = str.substr(1)
       } else {
         let num = 0, j = 5, i = 4
         while (j--) {
   ...
   

2. fromAscii85()

   String.prototype.fromAscii85 = function() {
     var ret = "";
     var str = this.replace(/\s+/g, "").replace("z", "!!!!!").slice(2, -2);
     for(var i=0; i<str.length; i+=5){
       var deficit = Math.max(0, 5+i-str.length);
       var nnn = 0;
       for(var j=0; j<5; j++){
         nnn = nnn*85 + (str.charCodeAt(i+j) || 117) - 33;
       var codes = [];
       for(var j=0; j<4; j++){
         codes.push(nnn%256);
         nnn = nnn/256 | 0;
       codes.reverse();
       var chunk = String.fromCharCode.apply(undefined, codes).slice(0, 4-deficit);
       ret+= chunk;
     return ret;
   

3. fromAscii85()

   String.prototype.fromAscii85 = function() {
     var str = this.slice(2, -2).replace(/z/g, '!!!!!').replace(/\s/g, '');
     var decoded = '';
     for(var i = 0, len = str.length; i < len; i+=5) {
       var n = 0;
       var us = 0;
       for(var j = 4; j >= 0; j--) {
         var c = str[j+i] || (us++, 'u'),
             code = c.charCodeAt(0) - 33;
   ...