Factors¶

Factors have the highest precedence in expression evaluation. In addition to ordinary immediate values and identifiers (→ token), they include the following.

true and false¶

true and false (true and false) are treated as integers with the values 1 and 0, respectively.

Avoid comparing true or false with other expressions. For example, instead of writing if(true != getBoolean()), write if(!getBoolean()). In logical expressions, "0 is false" and "anything other than 0 is true", not "1 is true". Also, TJS2 has no logical (Boolean) type, so no automatic conversion between numbers and Booleans takes place.

void¶

void means "nothing". It is used in various situations to indicate the absence of anything. It is different from null.

A freshly declared variable (one that has not been assigned anything) has this value.

When treated as a string, it becomes the empty string (''). When treated as a number, it becomes 0.

To compare void values, the === or !== (identity) operators are recommended.

null¶

null indicates something that is an object but "does not refer to any object". It is different from void.

Attempting to access a null object causes an error.

If you change a function's context to null using the incontextof operator, the function is then executed in the context of the place where it is called.

    var objmethod = obj.method;
    objmethod(); // executed in the context of obj
    objmethod = objmethod incontextof null; // change the context to null
    objmethod(); // executed on this (that is, the context at the calling site)

Infinity¶

Infinity represents infinity. Negative infinity is -Infinity.

NaN¶

NaN represents Not a Number. NaN is the numeric value obtained, for example, when the result of a calculation is invalid.

super¶

super represents the superclass of a class, within that class's methods/properties. Referring to it outside a class method/property, or inside a class that uses multiple inheritance, causes an error.

global¶

global represents the global object. Through it you can access variables declared outside all blocks, classes, functions that are not class methods, and so on.

    var v;
    function test(v)
    {
        global.v=v;  // set the global v to the argument v
    }

this¶

Within a class's methods and properties, this normally represents the object of that class itself.

The "context" specified explicitly or implicitly at call time is what this refers to.

Function Expressions¶

You can write a function inside an expression using function.

For details, see Functions.

Array Literals¶

You can write an Array class object on the spot inside an expression using **[ ]**.

For details, see Array class.

Dictionary Literals¶

You can write a Dictionary class object on the spot inside an expression using **%[ ]**.

For details, see Dictionary class.