Custom Studies Constructor

The Custom Study Constructor is a Function Constructor in terms of ES5. The library creates an instance of a custom study by applying operator new to the constructor. The constructor function is a mandatory field of custom study object. The library expects the constructor to create an instance of the study with one mandatory method - main() and one optional method - init(). Once the study is created the library calls init (if exists) and main sequentially with empty context to collect information about all vars (see below).

All functions in Constructor accept PineJS utility functions.

Arguments for both functions are context and inputCallback.

The context is an object, containing symbol info along with some useful methods to load/store symbol:

* - required

• new_sym(ticker*, period*, currencyCode, unitId) - is used to load new ticker
• select_sym(i*) - switch context to the other symbol received trough new_sym, where i is an index of the symbol (0 for the main series)
• new_var(value*) - creates an in-memory temporary storage with depth defined by first call new_var(value).get(n)
• new_unlimited_var(value*) - creates an in-memory temporary storage with unlimited depth

The inputCallback is an array of input values, placed in order of inputs in Metainfo.

init(context, inputCallback)

The init method is called only once during the lifetime of the study and designed to get additional info for the study.

this.init = function(context, inputCallback) {
    var symbol = '#EQUITY';
    var period = PineJS.Std.period(this._context);
    context.new_sym(symbol, period);
};

main(context, inputCallback)

The main is called every time the library wants to calculate the study. Also it's called for every bar of every symbol. Thus, if you request several additional symbols inside your indicator it will increase the count of runs.

main should return one of the following types:

• a single value; this is a shorthand of an array form with the only single item; example - 10 (the same as [10])
• an array of:
  • numbers - N-th number in this array is treated as value of n-th plot. Example: [10, 20].
  • objects with the structure { offset: number, value: number, }. The same as the numbers, but allows you to override the offset of every plot (note that offset of a certain plot should always be the same). Example: [{ value: 10, offset: 5, }, { value: 20, offset: 10, }].

this.main = function(ctx, inputCallback) {
    this._context = ctx;
    this._input = inputCallback;
    var inputValue1 = this._input(0);
    var inputValue2 = this._input(1);
    var zigzag1 = PineJS.Std.zigzag(inputValue1 / 100, inputValue2 / 2, this._context);
    var zigzag2 = PineJS.Std.zigzagbars(inputValue1 / 100, inputValue2 / 2, this._context);
    return [zigzag1, zigzag2];
};