'unneccessary escapement' article

Author: James Allardice

articles/unnecessary-escapement.md

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+<!---
+{
+    "titles": [
+        "Unnecessary escapement",
+        "Unexpected '\\'"
+    ],
+    "slugs": [
+        "unnecessary-escapement",
+        "unexpected-backslash"
+    ],
+    "linters": [
+        "jslint"
+    ],
+    "author": "jallardice"
+}
+-->
+
+### History
+
+This warning has existed in two forms in JSLint. It was introduced in the
+original version and has remained ever since. It is not present in JSHint or
+ESLint.
+
+ - In JSLint versions dated December 2010 and earlier the warning given is
+   "Unnecessary escapement"
+
+ - In more recent versions the message has changed to "Unexpected '\'"
+
+The situations that produce the warning have not changed despite changes to the
+text of the warning itself.
+
+### When do I get this error?
+
+The "Unnecessary escapement" error (and the alternative "Unexpected '\') is
+thrown when JSLint encounters **a string containing a unicode or hexadecimal
+escape sequence that could be replaced with the literal character**. In the
+following example we use the unicode escape sequence for the | (vertical line)
+character:
+
+<!---
+{
+    "linter": "jslint"
+}
+-->
+```javascript
+var title = "My Website \u007c Welcome";
+```
+
+### Why do I get this error?
+
+This error is raised to highlight a **potentially confusing piece of code**.
+When the character in question is safely represented without an escape sequence
+it is generally preferrable not to use an escape sequence because it makes the
+code easier to read. It would be difficult to know exactly what character is
+represented by `\u007c` in the above example without looking it up.
+
+The error is easily resolved by simply replacing unnecessary escape sequences
+with the appropriate characters:
+
+<!---
+{
+    "linter": "jslint"
+}
+-->
+```javascript
+var title = "My Website | Welcome";
+```