JavaScript資料型別強制轉換

我的個人部落格

基本資料：number, boolean, undefined, null, string;

引用資料：object;

當0.000…01，小數點後大於等於7位時會自動轉換成科學計數法

當20000…00，當整數部分大於等於22位時會自動轉換成科學計數法。

console.log(number(1));        //1

console.log(number(1e-7)); //1e-7
console.log(number(0b111)); //7
console.log(number(nan)); //nan

console.log(number(true));  //1

console.log(number(false)); //0

console.log(number(undefined)); //nan

console.log(number(null));    //0

//數字字串

console.log(number("123")); //123
console.log(number("-123")); //-123
console.log(number("12.3")); 
console.log(number("1e-7")); //1e-7
console.log(number("0xff")); //255
console.log(number("00123")); //123 
console.log(number(" 123")); //123
console.log(number("\t\n123")); //123

//數字+字元或全字元字串

console.log(number('a123')); //nan
console.log(number("false")); //nan
console.log(number("a123")); //nan

//空串或者空格字串

console.log(number("\t\n")); //0
console.log(number(" ")); //0
console.log(number("")); //0

console.log(number({}));  //nan

console.log(number([1])); //1
console.log(number([1,2])); //nan
cosole.log(number()); //0

無引數y時：

console.log(parseint(123));   //123

console.log(parseint(1e-7)); //1
console.log(parseint(0xff)); //255
console.log(parseint(nan)); //nan
console.log(parseint(0.00001)); //0

console.log(parseint(true));  //nan

console.log(parseint(false)); //nan
console.log(parseint(undefined)); //nan
console.log(parseint(null)); //nan

console.log(parseint(""));   //nan

console.log(parseint("-123")); //-123
console.log(parseint(" ")); //nan
console.log(parseint("\t\n")); //nan
console.log(parseint("a123")); //nan
console.log(parseint("123a")); //123

console.log(parseint());   //"[object object]"->nan

console.log(parseint()); //""->nan
console.log(parseint([1,2])); //"1,2"->//1

console.log(parseint("f",2));   //nan

console.log(parseint("11f",2); //3
console.log(parseint("123",37)); //nan
console.log(parseint("0xff",0)); //255
console.log(parseint("0xff",nan)); //255
console.log(parseint("ff",)); //nan

console.log(parsefloat(0xff));  //255

console.log(parsefloat("0xff")); //0 
console.log(parseint("0xff")); //255 個人猜測parseint(x,y)有y的存在所以能正確輸出
console.log(parsefloat(1e22)); //1e22
console.log(parsefloat(1e-7)); //1e-7
console.log(parsefloat("00123")); //123
console.log(parsefloat(" ")); //nan

console.log(string(null));  //"null"

console.log(0xff.tostring(2)); //"11111111"
console.log(oxff.tostring()); //"255" 不填預設10進製

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