我在JavaScript中寻找一种简单的方法来检查一个数字是否有小数点(以确定它是否为整数)。例如,
23 -> OK
5 -> OK
3.5 -> not OK
34.345 -> not OK
if(number is integer) {...}当前回答
以下是我的守卫库的摘录(灵感来自David Herman的Effective JavaScript):
var guard = {
guard: function(x) {
if (!this.test(x)) {
throw new TypeError("expected " + this);
}
}
// ...
};
// ...
var number = Object.create(guard);
number.test = function(x) {
return typeof x === "number" || x instanceof Number;
};
number.toString = function() {
return "number";
};
var uint32 = Object.create(guard);
uint32.test = function(x) {
return typeof x === "number" && x === (x >>> 0);
};
uint32.toString = function() {
return "uint32";
};
var decimal = Object.create(guard);
decimal.test = function(x) {
return number.test(x) && !uint32.test(x);
};
decimal.toString = function() {
return "decimal";
};
uint32.guard(1234); // fine
uint32.guard(123.4); // TypeError: expected uint32
decimal.guard(1234); // TypeError: expected decimal
decimal.guard(123.4); // fine
其他回答
parseInt(num) === num
当传递一个数字时，parseInt()只是将数字作为int返回:
parseInt(3.3) === 3.3 // false because 3 !== 3.3
parseInt(3) === 3 // true
如果value是字符串(例如from <input)，使用下面的语句:
Math.floor(value).toString() !== value
我将. tostring()添加到floor，使其也适用于value == "1 "的情况。(以十进制分隔符或其他字符串结束)。同时数学。floor总是返回一些值，因此. tostring()永远不会失败。
function isWholeNumber(num) {
return num === Math.round(num);
}
以下是我的守卫库的摘录(灵感来自David Herman的Effective JavaScript):
var guard = {
guard: function(x) {
if (!this.test(x)) {
throw new TypeError("expected " + this);
}
}
// ...
};
// ...
var number = Object.create(guard);
number.test = function(x) {
return typeof x === "number" || x instanceof Number;
};
number.toString = function() {
return "number";
};
var uint32 = Object.create(guard);
uint32.test = function(x) {
return typeof x === "number" && x === (x >>> 0);
};
uint32.toString = function() {
return "uint32";
};
var decimal = Object.create(guard);
decimal.test = function(x) {
return number.test(x) && !uint32.test(x);
};
decimal.toString = function() {
return "decimal";
};
uint32.guard(1234); // fine
uint32.guard(123.4); // TypeError: expected uint32
decimal.guard(1234); // TypeError: expected decimal
decimal.guard(123.4); // fine
//如何字节化它?
Number.prototype.isInt= function(){
return this== this>> 0;
}
我总是觉得javascript中的位操作符很糟糕
他们几乎不锻炼。
