Read Also: JavaScript String Methods How To Check the Variable of Type Undefined or Null? The null type shows that a variable is defined and has no value to that variable, whereas the undefined type doesn’t have value.
Note: When you only define the variable, then it is of an undefined type, and when you assign a null value to a variable, then it is of the object type. Then that variable is of the type object. When you declare a variable in your script, and you assign the value null to that variable. Then that variable is of the type undefined. Surprisingly, Steps 14 through 21 also do not apply to us, since Type(x) is null.When you declare a variable in your script but does not assign the value to that variable. Return false.Įvaluating the equality of null and 0, we immediately jump from Step 1 to Step 14 as the Types are not the same. 21.If Type( x) is Object and Type( y) is either String or Number, return the result of the comparison ToPrimitive( x)= y. 20.If Type( x) is either String or Number and Type( y) is Object, return the result of the comparison x = ToPrimitive( y). If Type( y) is Boolean, return the result of the comparison x = ToNumber( y). If Type( x) is Boolean, return the result of the comparison ToNumber( x)= y. 17.If Type( x) is String and Type( y) is Number, return the result of the comparison ToNumber( x)= y. 16.If Type( x) is Number and Type( y) is String, return the result of the comparison x = ToNumber( y). If x is undefined and y is null, return true. If x is null and y is undefined, return true. 13.Return true if x and y refer to the same object or if they refer to objects joined to each other (see 13.1.2). If Type( x) is Boolean, return true if x and y are both true or both false. 11.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). 7.If x is the same number value as y, return true. 4.If Type( x) is not Number, go to step 11. If Type( x) is different from Type( y), go to step 14. The = operator runs the statement through the Abstract Equality Comparison Algorithm, and returns true or false. The Abstract Equality Comparison Algorithm The ToPrimitive conversion follows this table. Steps 1 and 2 ask us to call ToPrimitive() on null and 0 respectively to convert these values to their primitive value types (such as Number and String). null > 0 // falseĪccording to the Spec, the relational operators > and 0. The Abstract Relational Comparison Algorithm
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