题解 | #简易计算器#

var Calculator = {
	init: function() {
		var that = this;
		if (!that.isInited) {
			that.isInited = true;
			// 保存操作信息
			// total: Number, 总的结果
			// next: String, 下一个和 total 进行运算的数据
			// action: String, 操作符号
			that.data = {
				total: 0,
				next: '',
				action: ''
			};
			that.bindEvent();
		}
	},
	bindEvent: function() {
		var that = this;
		// 请补充代码：获取 .cal-keyboard 元素
		var keyboardEl = document.querySelector('.cal-keyboard');
		keyboardEl && keyboardEl.addEventListener('click', function(event) {
			// 请补充代码：获取当前点击的dom元素
			var target = event.target;
			// 请补充代码：获取target的 data-action 值
			var action = target.dataset.action;
			// 请补充代码：获取target的内容
			var value = target.innerHTML;
			if (action === 'num' || action === 'operator') {
				that.result(value, action === 'num');
			}
		});
	},
	result: function(action, isNum) {
		var that = this;
		var data = that.data;
		if (isNum) {
			data.next = data.next === '0' ? action : (data.next + action);
			!data.action && (data.total = 0);
		} else if (action === '清空') {
			// 请补充代码：设置清空时的对应状态
			data.total = 0;
			data.next = '';
			data.action = '';
		} else if (action === '=') {
			if (data.next || data.action) {
				data.total = that.calculate(data.total, data.next, data.action);
				data.next = '';
				data.action = '';
			}
		} else if (!data.next) {
			data.action = action;
		} else if (data.action) {
			data.total = that.calculate(data.total, data.next, data.action);
			data.next = '';
			data.action = action;
		} else {
			data.total = +data.next || 0;
			data.next = '';
			data.action = action;
		}

		// ���补充代码：获取 .origin-value 元素
		var valEl = document.querySelector('.origin-value');
		valEl && (valEl.innerHTML = data.next || data.total || '0');
	},
	calculate: function(n1, n2, operator) {
		n1 = +n1 || 0;
		n2 = +n2 || 0;
		if (operator === '÷') {
            if (n2 == 0) {
				return 0
			}
			// 请补充代码：获取除法的结果
			if ((n1 / n2).toString().length > 5 && (n1 / n2).toString().indexOf('.') != -1) {
				if ((n1 / n2).toFixed(2).toString()[(n1 / n2).toFixed(2).toString().length - 1] == 0) {
					return Number((n1 / n2).toFixed(2).toString().substring(0, (n1 / n2).toFixed(2).toString().length - 1))
				} else {
					return Number((n1 / n2).toFixed(2))
				}
			} else {
				return Number(n1 / n2)
			}
		} else if (operator === 'x') {
			if ((n1 * n2).toString().length > 5 && (n1 * n2).toString().indexOf('.') != -1) {
				if ((n1 * n2).toFixed(2).toString()[(n1 * n2).toFixed(2).toString().length - 1] == 0) {
					return Number((n1 * n2).toFixed(2).toString().substring(0, (n1 * n2).toFixed(2).toString().length - 1))
				} else {
					return Number((n1 * n2).toFixed(2))
				}
			} else {
				return Number(n1 * n2)
			}
		} else if (operator === '+') {

			if ((n1 + n2).toString().length > 5 && (n1 + n2).toString().indexOf('.') != -1) {
				if ((n1 + n2).toFixed(2).toString()[(n1 + n2).toFixed(2).toString().length - 1] == 0) {
					return Number((n1 + n2).toFixed(2).toString().substring(0, (n1 + n2).toFixed(2).toString().length - 1))
				} else {
					return Number((n1 - n2).toFixed(2))
				}
			} else {
				return Number(n1 + n2)
			}
		} else if (operator === '-') {
			if ((n1 - n2).toString().length > 5 && (n1 - n2).toString().indexOf('.') != -1) {
				if ((n1 - n2).toFixed(2).toString()[(n1 - n2).toFixed(2).toString().length - 1] == 0) {
					return Number((n1 - n2).toFixed(2).toString().substring(0, (n1 - n2).toFixed(2).toString().length - 1))
				} else {
					return Number((n1 - n2).toFixed(2))
				}
			} else {
				return Number(n1 - n2)
			}
		}
	}
};
Calculator.init();