Explanation of boolean boolean value usage learning and related techniques in JavaScript

Two basic Boolean types in JavaScript:

1.true

2.false

The boolean value true means "true", and false means "false". Typical relational operators will return the results of a Boolean value. In addition, numeric values 0, -0, null, NaN, undefined, and null characters ("") of special values are all interpreted as false, and other values are interpreted as true.

 function isMonth(mon) { if ((mon >= 1) && (mon <= 12)) { return true; } else { return false; }}if (isMonth(mon)) { alert("OK");} else { alert("Please enter the correct month.");}

boolean = new Boolean(value)

Generates a boolean object. Set value to the initial value true or false . In order to conform to the idea that "all data types can generate objects" in object-oriented, JavaScript has prepared this class, but basically no one uses it.

xx = new Boolean(true);

All types in ECMAScript have values equivalent to the two values of true or false. You must convert a value to its corresponding Boolean.

Value, you can call the transformation function Boolean();

 Boolean(NaN);//falseBoolean(0);//falseBoolean('');//falseBoolean(null);//falseBoolean(undefined)//false

 !!"" // false!!0 // false!!null // false!!undefined // false!!NaN // false!!"hello" // true!!1 // true!!{} // true!![] // true