我以为TypeScript是(基本上) ECMAScript 6(又名)。( 2015)附加类型注释。
我的TypeScript编译器(1.6.2)抱怨了以下代码:
if (calc.distance > Number.EPSILON) {
...
}错误TS2339:属性'EPSILON‘在'NumberConstructor’类型中不存在。
类型是否有问题,还是TypeScript还没有真正成为ES6的超集?
我还没试过像Map,WeakMap,允诺,生成器,.
TypeScript是稍微落后于ES6,还是走到了另一个方向?我应该通过Babel运行TypeScript编译器输出吗?
刚从TypeScript开始,我不想背错马。
发布于 2015-10-06 10:31:09
为什么Number.EPSILON不存在于目标ES3和ES5
我以为TypeScript是(基本上) ECMAScript 6(又名)。( 2015)附加类型注释。
TypeScript是带有附加注释的ECMAScript。ES6的一些特性,如类、rest参数、lambdas、for of、let,在ES5或ES3中都有相当的代码,编译器可以为这些目标生成一些代码。但是新的API需要填充,编译器不添加任何运行时库(与Babel或Traceur不同)。
您的代码使用目标ES6编译。
对于目标ES3和ES5,您必须: 1/加载一个多填充(就像这个)和2/添加TypeScript编译器的定义。
查找TypeScript API的ES6定义
所以,你需要找到定义。以下是查找ES6 API定义的技巧。
编译器中已经定义了ES6 API的所有定义。我们可以利用它们。在节点目录中,打开文件lib/node_modules/typescript/lib/lib.es6.d.ts。然后,搜索EPSILON。您将找到一个接口NumberConstructor。以下是其代码(TS 1.6.2):
interface NumberConstructor {
/**
* The value of Number.EPSILON is the difference between 1 and the smallest value greater than 1
* that is representable as a Number value, which is approximately:
* 2.2204460492503130808472633361816 x 10−16.
*/
EPSILON: number;
/**
* Returns true if passed value is finite.
* Unlike the global isFininte, Number.isFinite doesn't forcibly convert the parameter to a
* number. Only finite values of the type number, result in true.
* @param number A numeric value.
*/
isFinite(number: number): boolean;
/**
* Returns true if the value passed is an integer, false otherwise.
* @param number A numeric value.
*/
isInteger(number: number): boolean;
/**
* Returns a Boolean value that indicates whether a value is the reserved value NaN (not a
* number). Unlike the global isNaN(), Number.isNaN() doesn't forcefully convert the parameter
* to a number. Only values of the type number, that are also NaN, result in true.
* @param number A numeric value.
*/
isNaN(number: number): boolean;
/**
* Returns true if the value passed is a safe integer.
* @param number A numeric value.
*/
isSafeInteger(number: number): boolean;
/**
* The value of the largest integer n such that n and n + 1 are both exactly representable as
* a Number value.
* The value of Number.MIN_SAFE_INTEGER is 9007199254740991 2^53 − 1.
*/
MAX_SAFE_INTEGER: number;
/**
* The value of the smallest integer n such that n and n − 1 are both exactly representable as
* a Number value.
* The value of Number.MIN_SAFE_INTEGER is −9007199254740991 (−(2^53 − 1)).
*/
MIN_SAFE_INTEGER: number;
/**
* Converts a string to a floating-point number.
* @param string A string that contains a floating-point number.
*/
parseFloat(string: string): number;
/**
* Converts A string to an integer.
* @param s A string to convert into a number.
* @param radix A value between 2 and 36 that specifies the base of the number in numString.
* If this argument is not supplied, strings with a prefix of '0x' are considered hexadecimal.
* All other strings are considered decimal.
*/
parseInt(string: string, radix?: number): number;
}只需将此代码添加到项目中即可。
发布于 2017-07-23 11:41:54
合法解决办法:
interface INumber {
EPSILON: any
}
declare var Number: INumber;https://stackoverflow.com/questions/32967380
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