Number.MAX_SAFE_INTEGER

¥Value

9007199254740991（9,007,199,254,740,991，或~9 千万亿）。

¥9007199254740991 (9,007,199,254,740,991, or ~9 quadrillion).

¥Description

双精度浮点格式 只有 52 位来表示 mantissa，因此它只能安全地表示 -(2⁵³ – 1) 和 2⁵³ – 1 之间的整数。在这种情况下，"安全的" 指的是准确表示整数并正确比较它们的能力。例如，Number.MAX_SAFE_INTEGER + 1 === Number.MAX_SAFE_INTEGER + 2 将计算为 true，这在数学上是不正确的。请参阅 Number.isSafeInteger() 了解更多信息。

¥Double precision floating point format only has 52 bits to represent the mantissa, so it can only safely represent integers between -(2⁵³ – 1) and 2⁵³ – 1. "Safe" in this context refers to the ability to represent integers exactly and to compare them correctly. For example, Number.MAX_SAFE_INTEGER + 1 === Number.MAX_SAFE_INTEGER + 2 will evaluate to true, which is mathematically incorrect. See Number.isSafeInteger() for more information.

由于 MAX_SAFE_INTEGER 是 Number 的静态属性，因此你始终将其用作 Number.MAX_SAFE_INTEGER，而不是作为数字值的属性。

¥Because MAX_SAFE_INTEGER is a static property of Number, you always use it as Number.MAX_SAFE_INTEGER, rather than as a property of a number value.

¥Examples

¥Return value of MAX_SAFE_INTEGER

Number.MAX_SAFE_INTEGER; // 9007199254740991

¥Relationship between MAX_SAFE_INTEGER and EPSILON

Number.EPSILON 为 2^-52，而 MAX_SAFE_INTEGER 为 2⁵³ – 1 — 两者均源自尾数宽度，即 53 位（最高位始终为 是 1）。将它们相乘得到的值非常接近（但不等于）2。

¥Number.EPSILON is 2^-52, while MAX_SAFE_INTEGER is 2⁵³ – 1 — both of them are derived from the width of the mantissa, which is 53 bits (with the highest bit always being 1). Multiplying them will give a value very close — but not equal — to 2.

Number.MAX_SAFE_INTEGER * Number.EPSILON; // 1.9999999999999998

¥See also

• core-js 中 Number.MAX_SAFE_INTEGER 的 Polyfill
• Number.MIN_SAFE_INTEGER
• Number.isSafeInteger()
• BigInt