JavaScript - Browser - The Document Object Model(Elements by Tag Name)

Eloquent JavaScript

開発環境

• macOS Sierra - Apple (OS)
• Emacs (Text Editor)
• JavaScript (プログラミング言語)
• Safari(Web browser)

Eloquent JavaScript(Marijn Haverbeke 著、No Starch Press)のPart 2(Browser)、Chapter 13(The Document Object Model)、Exercises(Elements by Tag Name)を取り組んでみる。

Exercises(Elements by Tag Name)

コード(Emacs)

JavaScript

'use strict';
let div = document.querySelector('#div0');
let getElementsByTagName = (node, tagName) => {
    let result = [],
        children = node.children;
    
    for (let i = 0, max = children.length; i < max; i += 1) {
        if (children[i].tagName.toLowerCase() == tagName.toLowerCase()) {
            result.push(children[i]);
        }
    }
    return result;
};
let node = document.getElementsByTagName('body')[0];

div.innerHTML = getElementsByTagName(node, 'div').join('<br>');