Number.parseFloat() - JavaScript
the number.parsefloat() method parses an argument and returns a floating point number.
...tract operation.
...whitespace character cannot be converted to a number.

parseFloat() - JavaScript
the parsefloat() function parses an argument (converting it to a string first if needed) and returns a floating point number.

A re-introduction to JavaScript (JS tutorial) - JavaScript
here, we see the parseint() function treat the first string as octal due to the leading 0, and the second string as hexadecimal due to the leading "0x".
...st string as octal due to the leading 0, and the second string as hexadecimal due to the leading "0x".
...an + 5; // nan you can test for nan using the built-in isnan() function: isnan(nan); // true javascript also has the special values infinity and -infinity: 1 / 0; // infinity -1 / 0; // -infinity you can test for infinity, -infinity and nan values using the built-in isfinite() function: isfinite(1 / 0); // false isfinite(-infinity); // false isfinite(nan); // false the parseint() and parsefloat() functions parse a string until they reach a character that isn't valid for the specified number format, then return the number parsed up to that point.

Functions - JavaScript
ermines whether the passed value is a finite number.
...passed value is a finite number.

Numbers and dates - JavaScript
between 1 and the smallest value greater than 1 that can be represented as a number (2.220446049250313e-16) number.min_safe_integer minimum safe integer in javascript (−253 + 1, or −9007199254740991) number.max_safe_integer maximum safe integer in javascript (+253 − 1, or +9007199254740991) methods of number method description number.parsefloat() parses a string argument and returns a floating point number.
...13e-16) number.min_safe_integer minimum safe integer in javascript (−253 + 1, or −9007199254740991) number.max_safe_integer maximum safe integer in javascript (+253 − 1, or +9007199254740991) methods of number method description number.parsefloat() parses a string argument and returns a floating point number.

New in JavaScript 1.1 - Archive of obsolete content
type properties on objects added.

ECMAScript 2015 support in Mozilla - Archive of obsolete content
math.fround() (firefox 26) math.log10(), math.log2(), math.log1p(), math.expm1(), math.cosh(), math.sinh(), math.tanh(), math.acosh(), math.asinh(), math.atanh(), math.hypot(), math.trunc(), math.sign(), math.cbrt() (firefox 25) additions to the number object number.isnan() (firefox 16) number.isfinite() (firefox 16) number.isinteger() (firefox 16) number.parseint() (firefox 25) number.parsefloat() (firefox 25) number.epsilon (firefox 25) number.max_safe_integer, number.min_safe_integer (firefox 31) number.issafeinteger() (firefox 32) additions to the object object object.prototype.__proto__ has been standardized object.is() (firefox 22) object.setprototypeof() (firefox 31) object.assign() (firefox 34) object.getownpropertysymbols() (firefox 33) additions to the date object ...

Element.clientTop - Web APIs
(offsettop and client area top) is the element's border.

Timing element visibility with the Intersection Observer API - Web APIs
lue using performance.now() into currenttime.

Grammar and types - JavaScript
owing statements: x = 'the answer is ' + 42 // "the answer is 42" y = 42 + ' is the answer' // "42 is the answer" with all other operators, javascript does not convert numeric values to strings.

Number - JavaScript
tatic methods number.isnan() determine whether the passed value is nan.

Standard built-in objects - JavaScript
t technologies overview.

JavaScript reference - JavaScript
this part of the javascript section on mdn serves as a repository of facts about the javascript language.