JavaScript has a Unicode problem · Mathias Bynens
The way JavaScript handles Unicode is… surprising, to say the least. This write-up explains the pain points associated with Unicode in JavaScript, provides solutions for common problems, and explains how the ECMAScript 6 standard improves the situation. Unicode basics Before we take a closer look at JavaScript, let’s make sure we’re all on the same page when it comes to Unicode. It’s easiest to th
Understanding ECMAScript 6 arrow functions - Human Who Codes
Posted at September 10, 2013 by Nicholas C. Zakas Tags: ECMAScript 6, Functions, JavaScript One of the most interesting new parts of ECMAScript 6 are arrow functions. Arrow functions are, as the name suggests, functions defined with a new syntax that uses an “arrow” (=>) as part of the syntax. However, arrow functions behave differently than traditional JavaScript functions in a number of importan
JavaScriptの+演算子の謎挙動に迫る » nmi.jp
console.log(+[]); // 0 console.log(+[3]); // 3 console.log(+[null]); // 0 console.log(+[undefined]); // 0 console.log(+["3"]); // 3 console.log(+[1,2]); // NaN console.log(+[true]); // NaN console.log(+[false]); // NaN なぜこのような処理になるのか、JavaScriptの仕様書（ECMA Script Specification 5th）から説明してみましょう。 まず最初、単項+演算子（Unary + Operator）を評価する際に、ToNumberを呼び出すのは前述したとおりです。仕様書の（11.4.6）に書かれています。ではToNumberとはどのような処理でしょうか。
Valid JavaScript variable names in ES5 · Mathias Bynens
Note: This article is based on the ECMAScript 5 specification. For the updated ES2015 version, see Valid JavaScript variable names in ES2015. Did you know var π = Math.PI; is syntactically valid JavaScript? I thought this was pretty cool, so I decided to look into which Unicode glyphs are allowed in JavaScript variable names, or identifiers as the ECMAScript specification calls them. Reserved word
[JavaScript]nullとundefinedとvoid演算子 / 文系大学的IT系の悲哀
2007-08-20 カテゴリ: Client Side タグ: JavaScript Tips JavaScriptのnullとundefinedとvoid演算子について調べたので忘れないうちにメモ。 typeof演算子 window.alert(typeof null); /* object */ window.alert(typeof undefined); /* undefined */ window.alert(typeof void('some value')); /* undefined */ nullはtypeof演算子に対してobjectという文字列を返すので要注意です。うっかり、 if (typeof obj == 'object') window.alert(obj.toString()); /* Bad Code */ のようなコードを書くと、objにnullが渡さ
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