odoo currency symbol display mechanism Monetary

//-------------------------------------------------------------------
basic_fields.js

init: function () {
    this._setCurrency();

//-------------------------------------------------------------------

_setCurrency: function () {
    var currencyField = this.nodeOptions.currency_field || this.field.currency_field || 'currency_id';
    var currencyID = this.record.data[currencyField] && this.record.data[currencyField].res_id;
    this.currency = session.get_currency(currencyID);
    this.formatOptions.currency = this.currency;

//-------------------------------------------------------------------
core/session.js

get_currency: function (currency_id) {
    return this.currencies[currency_id];
},

//-------------------------------------------------------------------
service/session.js

odoo.define('web.session', function (require) {
"use strict";

　　var Session = require('web.Session');
　　var modules = odoo._modules;

　　var session = new Session(undefined, undefined, {modules: modules, use_cors: false});
　　session.is_bound = session.session_bind();

　　return session;

});

// ------------------------------------------------ ------------------- 
call this.session_init in session_bind () in () 

call this.session_reload in this.session_init () in ()

session_reload: function () { 
    var _.extend Result = ({}, window.odoo.session_info); 
    Delete result.session_id; 
    _.extend (the this, Result); 
    return $ .when (); 
} 

when running into session_reload session_info has got res_currency currency information 

wfk! ! ! 
Go down to the bottom to engage in when not clear what it means: 
window.odoo What is this stuff? 
What window is?

interface Window extends EventTarget, WindowTimers, WindowSessionStorage, WindowLocalStorage, WindowConsole, GlobalEventHandlers, IDBEnvironment, WindowBase64, GlobalFetch, WindowOrWorkerGlobalScope, WindowEventHandlers {

//-------------------------------------------------------------------