How can I convert javascript to original english text?

I understand what you want to get, you want the human-readable JavaScript code, which can be modified and updated as per requirements. But the thing (as Mehdi has mentioned above in his answer; Solution 1) is that you cannot convert it back. This has been compressed and most of the "human-readable" content has been removed, because JavaScript interpreter doesn't care about that stuff.

The only stuff JavaScript interpreter cares about is the command of the program. Now, just for the sake of demonstration, the process can be specified like this, the "human-readable" JavaScript would be like:

var name = 'Afzaal Ahmad Zeeshan';

function sayHello() {
    alert('Hello, ' + name + '!');
}

This would be compressed to the following one:

function sayHello(){alert("Hello, "+name+"!")}var name="Afzaal Ahmad Zeeshan";

As Mehdi said, their functionality is similar, but the difference is that the later one would require less kBs to be sent over the network. What I think of this is, that this is similar to the differentiation process in the Calculus. You can differentiate a function, but when you have to bring it back to its original form, you get a constant field; which may be zero, may be any other integer value. Similarly, this code once has been minified, won't be converted back to its original form; the one in which it was written.

Minification (programming) - Wikipedia, the free encyclopedia[^]

The code can cleaned partially with Online JavaScript beautifier[^]
The result is

/* JS */
gapi.loaded_3(function(_) {
            var window = this;
            var Bk;
            _.zk = function(a) {
                if (!_.Tc(a)) return null;
                for (var b = {}, c = 0; c < a.length; c++) b[a[c]] = a[c];
                return b
            };
            _.Ak = function(a, b) {
                var c = a.length;
                if (c != b.length) return !1;
                for (var d = 0; d < c; ++d) {
                    var e = a.charCodeAt(d),
                        f = b.charCodeAt(d);
                    65 <= e && 90 >= e && (e += 32);
                    65 <= f && 90 >= f && (f += 32);
                    if (e != f) return !1
                }
                return !0
            };
            Bk = null;
            _.Ck = function(a) {
                if (null === Bk) {
                    var b = _.F("client/headers/response");
                    b || (b = _.F("googleapis/headers/response"));
                    Bk = _.zk(b)
                }
                if (null != Bk) {
                    if (Bk.hasOwnProperty(a)) return !0;
                    for (var c in Bk)
                        if (Bk.hasOwnProperty(c) && _.Ak(c, a)) return !0
                }
                return !1
            };
            _.Dk = function(a) {
                    a = String(a || "").split("\x00").join("");
                    for (var b = [], c = !0, d = 0, e = a.length; d < e; ++d) {
                        var f = a.charAt(d),
                            g = a.charCodeAt(d);
                        if (55296 <= g && 56319 >= g && d + 1 < e) {
                            var k = a.charAt(d + 1),
                                l = a.charCodeAt(d + 1);
                            56320 <= l && 57343 >= l && (f += k, g = 65536 + (g - 55296 << 10) + (l - 56320), ++d)
                        }
                        if (!(0 <= g && 1114109 >= g) || 55296 <= g && 57343 >= g || 64976 <= g && 65007 >= g || 65534 == (g & 65534)) g = 65533, f = String.fromCharCode(g);
                        k = !(32 <= g && 126 >= g) || " " == f || c && ":" == f || "\\" == f;
                        !c || "/" != f && "?" != f || (c = !1);
                        "%" == f && (d + 2 >= e ? k = !0 : (l = 16 * (0, window.parseInt)(a.charAt(d +
                            1), 16) + (0, window.parseInt)(a.charAt(d + 2), 16), 0 <= l && 255 >= l ? (g = l, f = 0 == g ? "" : "%" + (256 + l).toString(16).toUpperCase().substr(1), d += 2) : k = !0));
                        k && (f = (0, window.encodeURIComponent)(f), 1 >= f.length && (0 <= g && 127 >= g ? f = "%" + (256 + g).toString(16).toUpperCase().substr(1) : (g = 65533, f = (0, window.encodeURIComponent)(String.fromCharCode(g)))));
                        b.push(f)
                    }
                    a = b.join("");
                    a = a.split("#")[0];
                    a = a.split("?");
                    b = a[0].split("/");
                    c = [];
                    d = 0;
                    for (e = b.length; d < e; ++d) f = b[d], g = f.split("%2E").join("."), g = g.split((0, window.encodeURIComponent)("\uff0e")).join("."),

But this look like a program with no data, no message.