Question

我根本无法看到eventCards是如何初始化的。有人能告诉我吗？

ReferenceError：无法访问未初始化的变量。 7:26行

import tkinter as tk

def deposit():
    amount_display = tk.Text(root, width=5, height=5)
    amount_display.grid(column=7, row=2)
    response_text = 'You deposited ${}'.format(deposit_entry.get())
    amount_display.insert(tk.END, response_text)

def withdraw():
    pass

root = tk.Tk()
root.geometry('500x300')
root.title('Savings App')

# Labels

tk.Label(root, text='Deposit').grid(column=2, row=3)
tk.Label(root, text='Withdraw').grid(column=6, row=3)

# Entries

deposit_entry = tk.Entry(root)
deposit_entry.grid(column=2, row=4)

withdraw_entry = tk.Entry(root)
withdraw_entry.grid(column=6, row=4)

# Buttons

tk.Button(master=root, text='Deposit', command=deposit).grid(column=2, row=5)
tk.Button(master=root, text='Withdraw', command=withdraw).grid(column=6, row=5)

root.mainloop()

Answer 1

对于class变量，您需要在使用之前定义class。只需将类定义提升到顶部即可：

class Deck {
    constructor(cards) {
        this.cards = cards;
        this.deck = shuffle(cards);
    }

    shuffle(array) {
        ...
    }

    drawTopCard() {
        ...
    }
}

var eventCards = [
    'Do1',
    'Do2',
    'Do3',
    'Do4'
];
var eventDeck = new Deck(eventCards);

请参阅https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes

为什么抛出ReferenceError？

1 个答案: