Справица:Calculator.js

(function() {
    'use strict';
    var OPERATORS = {
        '+': function(a, b) {
            return a + b;
        },
        '-': function(a, b) {
            return a - b;
        },
        '*': function(a, b) {
            return a * b;
        },
        '/': function(a, b) {
            return a / b;
        },
        '%': function(a, b) {
            return a % b;
        },
        '^': function(a, b) {
            return Math.pow(a, b);
        },
        'max': Math.max,
        'min': Math.min,
        'floor': Math.floor,
        'ceil': Math.ceil,
        'round': Math.round
    };
    var SINGLE_OPERAND = ['floor', 'ceil', 'round'];
    var staticId = 0;
    var variables = {};
    function resolveVariable(calc, variable) {
        if (OPERATORS[variable]) {
            // You cannot name a variable the same as an operator.
            return null;
        }
        var num = Number(variable);
        if (!Number.isNaN(num)) {
            return num;
        }
        return variables[calc][variable];
    }
    function updateCalculator($calc, id) {
        // TODO: Multiple expressions, which are also variables.
        $calc.find('[data-expression]').each(function(_, el) {
            var $result = $(el);
            var stack = [];
            var expression = $result.attr('data-expression').split(' ').reverse();
            while (expression.length) {
                var item = expression.pop();
                if (OPERATORS[item]) {
                    if (SINGLE_OPERAND.includes(item)) {
                        stack.push(OPERATORS[item](stack.pop()));
                    } else {
                        var arg1 = stack.pop();
                        var arg2 = stack.pop();
                        stack.push(OPERATORS[item](arg2, arg1));
                    }
                } else {
                    stack.push(resolveVariable(id, item));
                }
            }
            var result = stack.pop();
            $result.text(result);
            var varName = $result.attr('data-variable');
            if (varName) {
                variables[id][varName] = result;
            }
        });
    }
    function changedVariable(event) {
        var $var = $(event.target);
        var varName = $var.parent().attr('data-variable');
        var $calc = $var.closest('.calculator');
        var calc = Number($calc.attr('data-id'));
        variables[calc][varName] = Number($var.val().trim());
        updateCalculator($calc, calc);
    }
    function hook($content) {
        $content.find('.calculator:not(.loaded)').each(function(_, el) {
            var $calc = $(el).addClass('loaded');
            var id = staticId++;
            variables[id] = {};
            $calc
                .attr('data-id', id)
                .find('[data-variable]')
                .each(function(__, el2) {
                    var $var = $(el2);
                    var varName = $var.attr('data-variable');
                    var defaultValue = $var.text().trim() || '0';
                    variables[id][varName] = Number(defaultValue);
                    if (Number.isNaN(variables[id][varName])) {
                        variables[id][varName] = 0;
                    }
                    if (!$var.attr('data-expression')) {
                        $var.html($('<input>', {
                            change: changedVariable,
                            max: $var.attr('data-max') || '100',
                            min: $var.attr('data-min') || '0',
                            step: $var.attr('data-step') || '0.001',
                            type: 'number',
                            value: defaultValue
                        }));
                    }
                });
            updateCalculator($calc, id);
        });
    }
    mw.hook('wikipage.content').add(hook);
})();