parseInt() 和 Number() 有什么区别? [英] What is the difference between parseInt() and Number()?

问题描述

如何parseInt() 和 Number() 将字符串转换为数字时表现不同?

How do parseInt() and Number() behave differently when converting strings to numbers?

推荐答案

嗯，它们在语义上不同，Number 作为函数调用的构造函数 执行类型转换和parseInt 执行解析，例如:

Well, they are semantically different, the Number constructor called as a function performs type conversion and parseInt performs parsing, e.g.:

// parsing:
parseInt("20px");       // 20
parseInt("10100", 2);   // 20
parseInt("2e1");        // 2

// type conversion
Number("20px");       // NaN
Number("2e1");        // 20, exponential notation

此外，parseInt 将忽略与当前使用的基数的任何数字都不对应的尾随字符.

Also parseInt will ignore trailing characters that don't correspond with any digit of the currently used base.

Number 构造函数不检测隐式八进制，但可以检测显式八进制表示法:

The Number constructor doesn't detect implicit octals, but can detect the explicit octal notation:

Number("010");         // 10
Number("0o10")         // 8, explicit octal

parseInt("010");       // 8, implicit octal
parseInt("010", 10);   // 10, decimal radix used

它可以处理十六进制的数字，就像parseInt:

And it can handle numbers in hexadecimal notation, just like parseInt:

Number("0xF");   // 15
parseInt("0xF"); //15

此外，一种广泛使用的用于执行数值类型转换的结构是 一元 + 运算符 (p. 72)，相当于将 Number 构造函数用作函数:

In addition, a widely used construct to perform Numeric type conversion, is the Unary + Operator (p. 72), it is equivalent to using the Number constructor as a function:

+"2e1";   // 20
+"0xF";   // 15
+"010";   // 10

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