From 06759cc8ea8231b3ee05f1f86b85f8c89209d06b Mon Sep 17 00:00:00 2001 From: Yasuaki Uechi Date: Mon, 14 Jan 2019 16:24:19 +0900 Subject: [PATCH] padsize --- _posts/2019-01-14-padsize.md | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 _posts/2019-01-14-padsize.md diff --git a/_posts/2019-01-14-padsize.md b/_posts/2019-01-14-padsize.md new file mode 100644 index 0000000..8cdf5a9 --- /dev/null +++ b/_posts/2019-01-14-padsize.md @@ -0,0 +1,30 @@ +--- +title: padStartにおけるpadSizeの求め方 +--- + +$$ +\textrm{padSize} = \lceil \log_{10}(\mathbf{arraySize} + 1) \rceil +$$ + +```js +const padSize = Math.ceil(Math.log10(arr.length + 1)) + +arr.forEach(async (item, index) => { + console.log(`${index.padStart(padSize, '0')}: ${item}`) +}) +``` + +結果は以下のようになる。 + +``` +01: item1 +02: item2 +03: item3 +04: item4 +05: item5 +06: item6 +07: item7 +08: item8 +09: item9 +10: item10 +```