Unary plus: +x does exactly the number coercion steps explained above to convert x.There are two ways to achieve nearly the same effect in JavaScript. The resulting primitive is then converted to a number. Objects are first converted to a primitive by calling their (with "number" as hint), valueOf(), and toString() methods, in that order.BigInts throw a TypeError to prevent unintended implicit coercion causing loss of precision.Empty or whitespace-only strings are converted to 0.In actual code, they are global variables. Infinity and -Infinity are recognized as literals.(In actual code, they "look like" part of the literal, but are actually separate unary operators.) However, the sign can only appear once, and must not be followed by whitespace. + and - are allowed at the start of the string to indicate its sign.A leading 0 digit does not cause the number to become an octal literal (or get rejected in strict mode).Leading and trailing whitespace/line terminators are ignored.There are some minor differences compared to an actual number literal: Strings are converted by parsing them as if they contain a number literal.The operation can be summarized as follows: Many built-in operations that expect numbers first coerce their arguments to numbers (which is largely why Number objects behave similarly to number primitives). More details on this are described in the ECMAScript standard. Integers can only be represented without loss of precision in the range -2 53 + 1 to 2 53 - 1, inclusive (obtainable via Number.MIN_SAFE_INTEGER and Number.MAX_SAFE_INTEGER), because the mantissa can only hold 53 bits (including the leading 1). Values higher than that are replaced with the special number constant Infinity. The largest value a number can hold is 2 1024 - 1 (with the exponent being 1023 and the mantissa being 0.1111… in base 2), which is obtainable via Number.MAX_VALUE. Therefore, the mantissa's precision is 2 -52 (obtainable via Number.EPSILON), or about 15 to 17 decimal places arithmetic above that level of precision is subject to rounding. The mantissa is stored with 52 bits, interpreted as digits after 1.… in a binary fractional number. Number = ( − 1 ) sign ⋅ ( 1 + mantissa ) ⋅ 2 exponent \text Thinking about it as scientific notation: The exponent is the power of 2 that the mantissa should be multiplied by. The mantissa (also called significand) is the part of the number representing the actual value (significant digits).
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