ReferenceError: document is not defined (in plain JavaScript)

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ReferenceError: document is not defined (in plain JavaScript)

posted Oct 17, 2021 in Technique[技术] by 深蓝 (71.8m points)

ReferenceError: document is not defined (in plain JavaScript)

I get the a "ReferenceError: document is not defined" while trying to

var body = document.getElementsByTagName("body")[0];

I have seen this before in others code and didn't cause any trouble. Why is it now? The companied HTML page is just a div inside the body.

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <link rel="stylesheet" type="text/css" href="css/quiz.css" />
    <script type="text/javascript" src="js/quiz.js"></script>
</head>
<body>

    <div id="divid">Next</div>

</body>
</html>

the code is the following:

(function(){
        var body = document.getElementsByTagName("body")[0];

        function Question(question, choices, correctAns) {
            this.question = question;
            this.choices = choices;
            this.correctAns = correctAns;
        }

        Question.prototype.checkAns = function(givenAns){
            if (this.correctAns === givenAns) {
                console.log("OK");
            }
        };

        function Quiz() {
            this.questions = [];
        }

        Quiz.prototype.showAllQuestions = function(){
            this.questions.forEach(function(questions){
                console.log(questions.question);
            });
        };

        Quiz.prototype.showQuiz = function(){
            this.questions.forEach(function(questions){

                for (var i=0; i < questions.choices.length; i+=1) {
                    body.innerHTML(
                            "<input type="radio" name="sex" value="male">" 
                            + questions.choices[i] + "<br>");
                }

            });
        };

        var q1 = new Question("What is red?", ["Color","Animal","Building"],1);
        var q2 = new Question("Most popular music?", ["Latin","Pop","Rock"],2);
        var quiz = new Quiz();

        quiz.questions.push(q1);
        quiz.questions.push(q2);
        quiz.showAllQuestions();


        })();

Try the whole code in this link HERE

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1 Reply

深蓝 · Answer 1 · 2021-10-16T22:34:16+0000

This happened with me because I was using Next JS which has server side rendering. When you are using server side rendering there is no browser. Hence, there will not be any variable window or document. Hence this error shows up.

Work around :

If you are using Next JS you can use the dynamic rendering to prevent server side rendering for the component.

import dynamic from 'next/dynamic'

const DynamicComponentWithNoSSR = dynamic(() => import('../components/List'), {
  ssr: false
})

export default () => <DynamicComponentWithNoSSR />

If you are using any other server side rendering library. Then add the code that you want to run at the client side in componentDidMount. If you are using React Hooks then use useEffects in the place of componentsDidMount.

import React, {useState, useEffects} from 'react';

const DynamicComponentWithNoSSR = <>Some JSX</>

export default function App(){

[a,setA] = useState();
useEffect(() => {
    setA(<DynamicComponentWithNoSSR/>)
  });


return (<>{a}<>)
}

References :

Categories

ReferenceError: document is not defined (in plain JavaScript)

ReferenceError: document is not defined (in plain JavaScript)

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