chore: add formateNum

Author: Simon he

src/formateNum.ts

@@ -0,0 +1,26 @@
+export function formateNum(number: number | string, decimals: number = 2, integer: 'floor' | 'ceil' = 'ceil') {
+  number = (number + '').replace(/[^0-9+-Ee.]/g, '');
+  const n = !isFinite(+number) ? 0 : +number,
+    prec = !isFinite(+decimals) ? 0 : Math.abs(decimals),
+    sep = ',',
+    dec = '.',
+    s = (prec ? toFixedFix(n, prec) : '' + Math.round(n)).split('.'),
+    re = /(-?\d+)(\d{3})/
+
+  while (re.test(s[0])) {
+    s[0] = s[0].replace(re, "$1" + sep + "$2");
+  }
+
+  if ((s[1] || '').length < prec) {
+    s[1] = s[1] || '';
+    s[1] += new Array(prec - s[1].length + 1).join('0');
+  }
+  return s.join(dec)
+
+  function toFixedFix(n: number, prec: number): string {
+    const k = Math.pow(10, prec);
+    return '' + (integer === 'ceil'
+      ? Math.ceil(n * k) / k
+      : Math.floor(n * k) / k)
+  };
+}