二進制/八進制
//宣告二進制
let binary=0B010101;
console.log(binary);//21
//宣告八進制
let octal=0o666;//第二個字母為o,大小寫都可以
console.log(octal);//438
判斷是否為數字
let isNum=11;
console.log(Number.isFinite(isNum));//true
console.log(Number.isFinite('eternity'));//false
console.log(Number.isFinite(NaN));//false
console.log(Number.isFinite(undefined));//false
console.log(Number.isFinite(null));//false
判斷是否為NaN
console.log(Number.isNaN(NaN));//true
判斷是否為整數
console.log(Number.isInteger(12));//true
console.log(Number.isInteger(12.1));//false
決議字串為數字
let str='918.2';
console.log(Number.parseInt(str));//918
console.log(Number.parseFloat(str));//918.2
最大安全整數
let posiNum=Math.pow(2,53)-1;
let nagiNum=-Math.pow(2,53)-1;
console.log(posiNum);//9007199254740991
console.log(nagiNum);//-9007199254740991
console.log(Number.MAX_SAFE_INTEGER);//9007199254740991
console.log(Number.MIN_SAFE_INTEGER);//-9007199254740991
console.log(Number.MAX_VALUE);//1.7976931348623157e+308
console.log(Number.MIN_VALUE);//5e-324
let posiNumUnsafe=Math.pow(2,53)+1;
console.log(Number.isSafeInteger(posiNumUnsafe));//false
console.log(Number.isSafeInteger(posiNum));//true
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