TypeScript将字符串转换为数字。

Anyone a suggestion on how to convert a string to a number in TypeScript?

有人有关于如何在打字稿中将字符串转换成数字的建议吗?

var aNumber : number = "1"; // --> Error

// Could this be done?
var defaultValue = 0;
var aNumber : number = "1".toInt32(defaultValue);

// Or ..
var defaultValue = 0;
var aNumber : number = StringToInt("1", defaultValue);

Update: I did some extra puzzling, the best sofar I've come up with: var aNumber : number = ( "1") * 1;

更新:我做了一些额外的令人困惑的工作，目前为止我所做的最好的工作:var aNumber: number =(“1”)* 1;

checking if a string is numeric is answered here: In Typescript, How to check if a string is Numeric.

检查字符串是否为数字的回答在这里:在Typescript中，如何检查字符串是否为数字。

7 个解决方案

#1

455

You can use the parseInt or parseFloat functions, or simply use the unary + operator:

您可以使用parseInt或parseFloat函数，也可以使用一元+运算符:

var x = "32";
var y = +x; // y: number

#2

543

The Typescript way to do this would be:

打字稿的方式是:

Number('1234') // 1234
Number('9BX9') // NaN

as answered here: https://*.com/a/23440948/2083492

在这里回答:https://*.com/a/23440948/2083492

#3

For our fellow Angular users:

对于我们的角用户来说:

Within a template, Number(x) and parseInt(x) throws an error, and +x has no effect. Valid casting will be x*1 or x/1.

在模板中，Number(x)和parseInt(x)抛出一个错误，+x没有影响。有效施法为x*1或x/1。

#4

Expounding on what Ryan said, TypeScript embraces the JavaScript idioms in general.

在解释Ryan所说的内容时，打字稿大体上包含了JavaScript习惯用法。

var n = +"1"; // the unary + converts to number
var b = !!"2"; // the !! converts truthy to true, and falsy to false
var s = ""+3; // the ""+ converts to string via toString()

All the interesting in-depth details at JavaScript Type Conversion.

JavaScript类型转换的所有有趣的深入细节。

#5

As shown by other answers here, there are multiple ways to do the conversion:

如其他答案所示，转换有多种方式:

Number('123');
+'123';
parseInt('123');
parseFloat('123.45')

I'd like to mention one more thing on parseInt though.

我想再提一件关于parseInt的事。

When using parseInt, it makes sense to always pass the radix parameter. For decimal conversion, that is 10. This is the default value for the parameter, which is why it can be omitted. For binary, it's a 2 and 16 for hexadecimal. Actually, any radix between and including 2 and 36 works.

使用parseInt时，总是传递基数参数是有意义的。对于十进制转换，这是10。这是参数的默认值，因此可以省略它。对于二进制，它是十六进制的2和16。实际上，2和36之间的任何基数都可以。

parseInt('123')         // 123 (don't do this)
parseInt('123', 10)     // 123 (much better)

parseInt('1101', 2)     // 13
parseInt('0xfae3', 16)  // 64227

The parseInt function, well, parses strings to convert them to numbers. In some JS implementations, parseInt parses leading zeros as octal:

parseInt函数解析字符串将其转换为数字。在一些JS实现中，parseInt将前导0解析为八进制:

Although discouraged by ECMAScript 3 and forbidden by ECMAScript 5, many implementations interpret a numeric string beginning with a leading 0 as octal. The following may have an octal result, or it may have a decimal result. Always specify a radix to avoid this unreliable behavior.

虽然ECMAScript 3不支持，ECMAScript 5也不允许，但是很多实现都将以0开头的数字字符串解释为八进制。以下可能有八进制结果，也可能有十进制结果。总是指定一个基数来避免这种不可靠的行为。

— MDN

——MDN

The fact that code gets clearer is a nice side effect of specifying the radix parameter.

代码变得更清晰是指定基数参数的一个很好的副作用。

Since parseFloat only parses numeric expressions in radix 10, there's no need for a radix parameter here.

由于parseFloat只解析基数10中的数值表达式，所以这里不需要基数参数。

#6

You can follow either of the following ways.

您可以采用以下任何一种方法。

var str = '54';

var num = +str; //easy way by using + operator
var num = parseInt(str); //by using the parseInt operation

#7

There are inbuilt functions like parseInt(), parseFloat() and Number() in Typescript, you can use those.

在类型文件中有一些内置函数，如parseInt()、parseFloat()和Number()，您可以使用它们。

#1

455