Where to find documentation that explain any part of the code as the following code

hi all
please if any one know any documentation resources either pdf,txt,doc or webpage links that explain the code of Frappe/Erpnext specially code related to Frappe framework code
please tell us and paste it in replay .
For example:
the following explanation of this code:

Syntax

frappe.ui.form.on([DocType], {

[trigger]: function(frm) {

    [function];

}

});

Replace [DocType] with the one you want to use, in quotations. Example: frappe.ui.form.on(“Sales Order”, { or frappe.ui.form.on(“Purchase Order”, {

Replace [Trigger] with the one you want to use. Example: company: function(frm) { This would trigger the function when the company field is modified or onload: function(frm) { This would trigger the function when the document is loaded.

List of Triggers

Field Names (see the company example above)

onload

refresh

validate

onsubmit

onload_post_render

Example:

frappe.ui.form.on(“Salary Slip”, {

company: function(frm) {

// this function is called when the value of company is changed.

}

});