javascript - 为什么这段代码没有按预期工作？

Question

let x;
console.log("shubham" == true );  // gives false
"shubham" ? x=2 : x=3;
console.log(x); // gives 2, so "shubham" must be true?  

//我希望得到值3

Answer 1

当你使用它时:

"shubham" == true

比较前，true变为1，所以实际比较是

"shubham" == 1

所以，它给出了错误；

这本书:

When performing conversions, the equal and not-equal operators follow these basic rules:

If an operand is a Boolean value, convert it into a numeric value before checking for equality. A value of false converts to 0, whereas a value of true converts to 1.

If one operand is a string and the other is a number, attempt to convert the string into a number before checking for equality.

当你使用它时:

"shubham" ? x=2 : x=3;

工作方式如下:

Boolean("shubham")?x=2:x=3

所以，它给你 x=2;

这本书:

variable = boolean_expression ? true_value : false_value;

This basically allows a conditional assignment to a variable depending on the evaluation of the boolean_expression. If it’s true, then true_value is assigned to the variable; if it’s false, then false_value is assigned to the variable.

这本书:

Professional JavaScript for Web Developers.3rd.Edition.Jan.2012