The propertyIsEnumerable() method of Object instances returns a boolean indicating whether the specified property is this object's enumerable own property.

The split() method of String values takes a pattern and divides this string into an ordered list of substrings by searching for the pattern, puts these substrings into an array, and returns the array.

The includes() method of Array instances determines whether an array includes a certain value among its entries, returning true or false as appropriate.

The sort() method of Array instances sorts the elements of an array in place and returns the reference to the same array, now sorted. The default sort order is ascending, built upon converting the elements into strings, then comparing their sequences of UTF-16 code units values.

The concat() method of Array instances is used to merge two or more arrays. This method does not change the existing arrays, but instead returns a new array.

The flat() method of Array instances creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.

The splice() method of Array instances changes the contents of an array by removing or replacing existing elements and/or adding new elements in place.

This page describes JavaScript's lexical grammar. JavaScript source text is just a sequence of characters — in order for the interpreter to understand it, the string has to be parsed to a more structured representation. The initial step of parsing is called lexical analysis, in which the text gets scanned from left to right and is converted into a sequence of individual, atomic input elements. Some input elements are insignificant to the interpreter, and will be stripped after this step — they include white space and comments. The others, including identifiers, keywords, literals, and punctuators (mostly operators), will be used for further syntax analysis. Line terminators and multiline comments are also syntactically insignificant, but they guide the process for automatic semicolons insertion to make certain invalid token sequences become valid.

The xml:lang attribute specifies the primary language used in contents and attributes containing text content of particular elements.

SVG supports the built-in XML xml:space attribute to handle whitespace characters inside elements. Child elements inside an element may also have an xml:space attribute that overrides the parent's one.