javascript 中 字符串 0 '0' 的布尔值
'0'==false;//true
'0'||1;//'0'
'0'?true:false;//true
内部到底有什么不同？
写回答
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找到答案了：http://ecma262-5.com/ELS5_HTML.htm#Section_11.9.3
11.9.3 The Abstract Equality Comparison Algorithm
The comparison x == y , where x and y are values, produces true or false . Such a comparison is performed as follows:
If Type(x) is the same as Type(y), then
If Type(x) is Undefined, return true.
If Type(x) is Null, return true.
If Type(x) is Number, then
If x is NaN, return false.
If y is NaN, return false.
If x is the same Number value as y, return true.
If x is + and y is −, return true.
If x is − and y is +, return true.
Return false.
If Type(x) is String, then return true if x and y are exactly the same sequence of characters (same length and same characters in corresponding positions). Otherwise, return false.
If Type(x) is Boolean, return true if x and y are both true or both false. Otherwise, return false.
Return true if x and y refer to the same object. Otherwise, return false.
If x is null and y is undefined, return true.
If x is undefined and y is null, return true.
If Type(x) is Number and Type(y) is String, return the result of the comparison x == ToNumber(y).
If Type(x) is String and Type(y) is Number, return the result of the comparison ToNumber(x) == y.
If Type(x) is Boolean, return the result of the comparison ToNumber(x) == y.
If Type(y) is Boolean, return the result of the comparison x == ToNumber(y).
If Type(x) is either String or Number and Type(y) is Object, return the result of the comparison x == ToPrimitive(y).2019-07-17 19:56:49赞同 展开评论 打赏
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