Variables¶

Variables in TJS2 are declared with the var keyword. In TJS2, a variable cannot be used unless it has been declared.

The form of the var keyword is as follows.

　var variable_name;

You can specify several variable names separated by , (commas). If a variable needs an initial value, use the form

　var variable_name = initial_value;

to assign an initial value to the variable.

    var variable=0;
    var var2=variable+2;
    var var3="this is var3.";
    var var1,var2,var3;
    var a=0,b=1,c=3;

You do not need to specify a type when declaring a variable. It takes on the type of whatever is assigned to it. Types are also converted automatically during calculations and depending on context.

Variable Names¶

Any identifier is valid as a variable name.

    var ampan;
    var 123a;  // NG: starts with a digit
    var function; // NG: function is a reserved word
    var function1; // OK: contains a reserved word but is not the reserved word itself
    var 変数その一; // so-called full-width (Japanese) characters can also be used

Declaring a Variable Twice¶

Declaring a variable with the same name more than once does not cause an error. However, if an initial value is given in a second or later declaration, that initial value is assigned to the variable. If no initial value is given in a second or later declaration, the variable becomes void.

    var a=0;
    var a; // second declaration (no error; a becomes void)
    var a=-1; // third declaration (no error; -1 is assigned to a)

Variable Scope¶

A variable declared inside a part enclosed in { } (a block) is valid only within that block; that is, it is a local variable.

Also, unlike C, there is no restriction on where variables can be declared.

    while(t--)
    {
        var ratio=t/all; // declare variable 'ratio'
        setRatio(ratio);
    }

    // by the time control reaches here, 'ratio' has been removed

    var test; // variables can be declared here too

When a variable with the same name as a variable outside the block is declared inside the block, only the newly declared variable can be accessed within that block.

    var ratio=0;
    if(flag)
    {
        var ratio; // same name as a variable declared outside the block

        ratio=buf.position / buf.totalTime; // only the ratio inside the block can be accessed
        setRatio(ratio);
    }

    // leaving the block removes the inner ratio, but the outer ratio is unchanged
    ratio=-1;

Note: A variable declared with var outside every scope (this is called the global scope) becomes a member of the global object.