我不知道为什么我的函数不能读取quotesdata

Question

i don't why my function in addEventListener can not read quotesdata , this what i see in the console :

Uncaught TypeError: quotesData[currentQuote] is undefined and this is js code :

quotesData = [
    {
        quote : `There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.`,
        name : 'Albert Einstein '
    },
    {
        quote : `Good friends, good books, and a sleepy conscience: this is the ideal life.`,
        name : 'Mark Twain'
    },
    {
        quote : `Life is what happens to us while we are making other plans.`,
        name : 'Allen Saunders '
    },
    {
        quote : `It's not the load that breaks you down, it's the way you carry it.`,
        name : 'Lou Holt'
    },
    {
        quote : `Try not to become a man of success. Rather become a man of value.`,
        name : 'Albert Einstein '
    },   
]
/* important variables */ 
let currentQuote = quotesData[0];
const quoteText = document.getElementById('quote');
const quotebtn = document.getElementById('q-btn');
const quotespan = document.getElementById('q-span');

/* this the main function its usefulness is show a quote from quotesData evrey time you click on the button*/ 
quotebtn.addEventListener('click' , () => {
    quoteText.innerText = quotesData[currentQuote].quote;
    quotespan.innerText = quotesData[currentQuote].name; 
    
    currentQuote = (currentQuote + 1 ) % quotesData.length;
});

Answer 1

You need to store the index, not the object of the current quote in currentQuote :

 quotesData = [ { quote : `There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.`, name : 'Albert Einstein ' }, { quote : `Good friends, good books, and a sleepy conscience: this is the ideal life.`, name : 'Mark Twain' }, { quote : `Life is what happens to us while we are making other plans.`, name : 'Allen Saunders ' }, { quote : `It's not the load that breaks you down, it's the way you carry it.`, name : 'Lou Holt' }, { quote : `Try not to become a man of success. Rather become a man of value.`, name : 'Albert Einstein ' }, ] /* important variables */ let currentQuote = 0; const quoteText = document.getElementById('quote'); const quotebtn = document.getElementById('q-btn'); const quotespan = document.getElementById('q-span'); /* this the main function its usefulness is show a quote from quotesData evrey time you click on the button*/ quotebtn.addEventListener('click' , () => { quoteText.innerText = quotesData[currentQuote].quote; quotespan.innerText = quotesData[currentQuote].name; currentQuote = (currentQuote + 1) % quotesData.length; });

 <button id="q-btn">New quote</button> <div id="q-span"></div> <div id="quote"></div>

Answer 2

I'm not sure, but I think that you may be using the key ` and not the key '. I think that you might want to change all of the quotes at the beginning and end to " just to be safe. I'm probably not right, but it's the only solution I can think of.