From eea856e341a5381c6a5744db1ee6fe590cf8ffd3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E8=BF=B7=E6=B8=A1?= <justjavac@gmail.com>
Date: Wed, 4 Sep 2019 22:32:28 +0800
Subject: [PATCH] Refactoring using padEnd and padStart (denoland/deno_std#583)

Original: https://github.com/denoland/deno_std/commit/4e21ace634b635ef540adc7727cd3d8eb9df99bd
---
 fmt/sprintf.ts | 23 ++++++++++-------------
 1 file changed, 10 insertions(+), 13 deletions(-)

diff --git a/fmt/sprintf.ts b/fmt/sprintf.ts
index 596f90c858..e1edb13479 100644
--- a/fmt/sprintf.ts
+++ b/fmt/sprintf.ts
@@ -365,14 +365,12 @@ class Printf {
 
   pad(s: string): string {
     const padding = this.flags.zero ? "0" : " ";
-    while (s.length < this.flags.width) {
-      if (this.flags.dash) {
-        s += padding;
-      } else {
-        s = padding + s;
-      }
+
+    if (this.flags.dash) {
+      return s.padEnd(this.flags.width, padding);
     }
-    return s;
+
+    return s.padStart(this.flags.width, padding);
   }
   padNum(nStr: string, neg: boolean): string {
     let sign: string;
@@ -393,13 +391,12 @@ class Printf {
     const pad = zero ? "0" : " ";
     const len = zero ? this.flags.width - sign.length : this.flags.width;
 
-    while (nStr.length < len) {
-      if (this.flags.dash) {
-        nStr += pad; // left justify - right pad
-      } else {
-        nStr = pad + nStr; // right just - left pad
-      }
+    if (this.flags.dash) {
+      nStr = nStr.padEnd(len, pad);
+    } else {
+      nStr = nStr.padStart(len, pad);
     }
+
     if (zero) {
       // see above
       nStr = sign + nStr;