无JIRA 回复number的polyfill

3 years ago · b7c491ac20
1 changed files with 142 additions and 0 deletions
--- a/src/polyfill/number.js
+++ b/src/polyfill/number.js
@ -0,0 +1,142 @@
+if (!Number.prototype.toFixed || (0.00008).toFixed(3) !== "0.000" ||
+    (0.9).toFixed(0) === "0" || (1.255).toFixed(2) !== "1.25" ||
+    (1000000000000000128).toFixed(0) !== "1000000000000000128") {
+    (function () {
+        var base, size, data, i;
+        base = 1e7;
+        size = 6;
+        data = [0, 0, 0, 0, 0, 0];
+        function multiply (n, c) {
+            var i = -1;
+            while (++i < size) {
+                c += n * data[i];
+                data[i] = c % base;
+                c = Math.floor(c / base);
+            }
+        }
+
+        function divide (n) {
+            var i = size, c = 0;
+            while (--i >= 0) {
+                c += data[i];
+                data[i] = Math.floor(c / n);
+                c = (c % n) * base;
+            }
+        }
+
+        function toString () {
+            var i = size;
+            var s = "";
+            while (--i >= 0) {
+                if (s !== "" || i === 0 || data[i] !== 0) {
+                    var t = String(data[i]);
+                    if (s === "") {
+                        s = t;
+                    } else {
+                        s += "0000000".slice(0, 7 - t.length) + t;
+                    }
+                }
+            }
+            return s;
+        }
+
+        function pow (x, n, acc) {
+            return (n === 0 ? acc : (n % 2 === 1 ? pow(x, n - 1, acc * x)
+                : pow(x * x, n / 2, acc)));
+        }
+
+        function log (x) {
+            var n = 0;
+            while (x >= 4096) {
+                n += 12;
+                x /= 4096;
+            }
+            while (x >= 2) {
+                n += 1;
+                x /= 2;
+            }
+            return n;
+        }
+
+        Number.prototype.toFixed = function (fractionDigits) {
+            var f, x, s, m, e, z, j, k;
+            f = Number(fractionDigits);
+            f = f !== f ? 0 : Math.floor(f);
+
+            if (f < 0 || f > 20) {
+                throw new RangeError("Number.toFixed called with invalid number of decimals");
+            }
+
+            x = Number(this);
+
+            if (x !== x) {
+                return "NaN";
+            }
+
+            if (x <= -1e21 || x > 1e21) {
+                return String(x);
+            }
+
+            s = "";
+
+            if (x < 0) {
+                s = "-";
+                x = -x;
+            }
+
+            m = "0";
+
+            if (x > 1e-21) {
+                // 1e-21<x<1e21
+                // -70<log2(x)<70
+                e = log(x * pow(2, 69, 1)) - 69;
+                z = (e < 0 ? x * pow(2, -e, 1) : x / pow(2, e, 1));
+                z *= 0x10000000000000;// Math.pow(2,52);
+                e = 52 - e;
+
+                // -18<e<122
+                // x=z/2^e
+                if (e > 0) {
+                    multiply(0, z);
+                    j = f;
+
+                    while (j >= 7) {
+                        multiply(1e7, 0);
+                        j -= 7;
+                    }
+
+                    multiply(pow(10, j, 1), 0);
+                    j = e - 1;
+
+                    while (j >= 23) {
+                        divide(1 << 23);
+                        j -= 23;
+                    }
+                    divide(1 << j);
+                    multiply(1, 1);
+                    divide(2);
+                    m = toString();
+                } else {
+                    multiply(0, z);
+                    multiply(1 << (-e), 0);
+                    m = toString() + "0.00000000000000000000".slice(2, 2 + f);
+                }
+            }
+
+            if (f > 0) {
+                k = m.length;
+
+                if (k <= f) {
+                    m = s + "0.0000000000000000000".slice(0, f - k + 2) + m;
+                } else {
+                    m = s + m.slice(0, k - f) + "." + m.slice(k - f);
+                }
+            } else {
+                m = s + m;
+            }
+
+            return m;
+        };
+
+    })();
+}