本篇仅对隐式转换中的知识点做记录,不深入展开介绍.
[点击查看图片](https://www.processon.com/view/link/60dd8a751e085359888c0d9d)
注意: PreferredType默认为Number,当input为Date类型数据时,PreferredType为String
- valueOf()
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| var num = new Number('123');
num.valueOf(); // 123
var str = new String('12df');
str.valueOf(); // '12df'
var bool = new Boolean('fd');
bool.valueOf(); // true
var a = new Date();
a.valueOf(); // 1532234132475
var a = new Array();
a.valueOf(); //[]
a.valueOf() === a; // true
var b = new Object({});
b.valueOf(); //{}
b.valueOf() === b; // true
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2.toString()
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| var num = new Number('123sd');
num.toString(); // 'NaN'
var str = new String('12df');
str.toString(); // '12df'
var bool = new Boolean('fd');
bool.toString(); // 'true'
var arr = new Array(1,2);
arr.toString(); // '1,2'
var d = new Date();
d.toString(); // "Sun Jul 22 2018 12:38:42 GMT+0800 (中国标准时间)"
var func = function () {}
func.toString(); // "function () {}"
var obj = new Object({});
obj.toString(); // "[object Object]"
Math.toString(); // "[object Math]"
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| type(x)|type(y)|result(x==y)|
|-| :- | :-: | -: |
|null|undefined|true|
|String|Number|Number(x)==y|
|Boolean|any|Number(x)==y|
|Object| String or Number|toPrimitive(x)==y|
|NaN|any|false|
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| []==0; //true
1.[]=>ValueOf([])=>[];
2.[]=>toSring([])=>""
""==0
3.""=>Number("")=>0
0==0
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| []=="0" //false
1.[]=>ValueOf([])=>[];
2.[]=>toSring([])=>""
""=="0"
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| type(x)|type(y)|result(x+y)|
|-| :- | :-: | -: |
|String|any|x+toString(y)|
|Object|any|toString(x)+toString(y)|
|Boolean|Number or Boolean|Number(x)+Number(y)|
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| "1ac"+true // "1actrue"
"1ac"+[] // "1ac"
"1ac"+[1,'a'] // "1ac1,a"
"1ac"+{} // "1ac[object Object]"
{}+true // "[object Object]true"
{}+[] // "[object Object]"
true+true // 2
true+1 // 2
false+1 // 1
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