{"componentChunkName":"component---src-templates-blog-post-js","path":"/Interview/javascript/","result":{"data":{"site":{"siteMetadata":{"title":"Nans' blogs"}},"markdownRemark":{"id":"90b72ec8-65b1-59d4-addb-9f10e1807307","excerpt":"Those are just some random questions I sometimes ask when evaluating junior developers. ⭐ What is the difference between  and  ? What is the output ?  ⭐⭐ What…","html":"<p>Those are just some random questions I sometimes ask when evaluating junior developers.</p>\n<p>⭐</p>\n<ul>\n<li>What is the difference between <code class=\"language-text\">==</code> and <code class=\"language-text\">===</code> ?</li>\n<li>\n<p>What is the output ?</p>\n<div class=\"gatsby-highlight\" data-language=\"javascript\"><pre class=\"language-javascript\"><code class=\"language-javascript\"><span class=\"token keyword\">const</span> animals <span class=\"token operator\">=</span> <span class=\"token punctuation\">{</span><span class=\"token punctuation\">}</span><span class=\"token punctuation\">;</span>\n<span class=\"token punctuation\">[</span><span class=\"token string\">'zebra'</span><span class=\"token punctuation\">,</span> <span class=\"token string\">'horse'</span><span class=\"token punctuation\">]</span><span class=\"token punctuation\">.</span><span class=\"token function\">forEach</span><span class=\"token punctuation\">(</span><span class=\"token keyword\">function</span><span class=\"token punctuation\">(</span><span class=\"token parameter\">k</span><span class=\"token punctuation\">)</span> <span class=\"token punctuation\">{</span>\n\tanimals<span class=\"token punctuation\">[</span>k<span class=\"token punctuation\">]</span> <span class=\"token operator\">=</span> <span class=\"token keyword\">undefined</span><span class=\"token punctuation\">;</span>\n<span class=\"token punctuation\">}</span><span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span>\nconsole<span class=\"token punctuation\">.</span><span class=\"token function\">log</span><span class=\"token punctuation\">(</span>animals<span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span> <span class=\"token operator\">?</span></code></pre></div>\n</li>\n</ul>\n<p> ⭐⭐</p>\n<ul>\n<li>\n<p>What is the difference ?</p>\n<div class=\"gatsby-highlight\" data-language=\"javascript\"><pre class=\"language-javascript\"><code class=\"language-javascript\"><span class=\"token punctuation\">[</span><span class=\"token number\">1</span><span class=\"token punctuation\">,</span><span class=\"token number\">2</span><span class=\"token punctuation\">,</span><span class=\"token number\">3</span><span class=\"token punctuation\">]</span><span class=\"token punctuation\">.</span><span class=\"token function\">map</span><span class=\"token punctuation\">(</span><span class=\"token comment\">/*() => { ... }*/</span><span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span>\n<span class=\"token punctuation\">[</span><span class=\"token number\">1</span><span class=\"token punctuation\">,</span><span class=\"token number\">2</span><span class=\"token punctuation\">,</span><span class=\"token number\">3</span><span class=\"token punctuation\">]</span><span class=\"token punctuation\">.</span><span class=\"token function\">forEach</span><span class=\"token punctuation\">(</span><span class=\"token comment\">/*() => { ... }*/</span><span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span></code></pre></div>\n</li>\n<li>\n<p>What is the output ?</p>\n<div class=\"gatsby-highlight\" data-language=\"javascript\"><pre class=\"language-javascript\"><code class=\"language-javascript\"><span class=\"token keyword\">const</span> numbersAndStuff <span class=\"token operator\">=</span> <span class=\"token punctuation\">[</span><span class=\"token number\">0</span><span class=\"token punctuation\">,</span> <span class=\"token number\">2</span><span class=\"token punctuation\">,</span> <span class=\"token number\">4</span><span class=\"token punctuation\">,</span> <span class=\"token number\">6</span><span class=\"token punctuation\">,</span> <span class=\"token keyword\">undefined</span><span class=\"token punctuation\">]</span><span class=\"token punctuation\">;</span>\n<span class=\"token keyword\">const</span> filtered <span class=\"token operator\">=</span> numbersAndStuff<span class=\"token punctuation\">.</span><span class=\"token function\">filter</span><span class=\"token punctuation\">(</span><span class=\"token parameter\">element</span> <span class=\"token operator\">=></span> element<span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span>\nconsole<span class=\"token punctuation\">.</span><span class=\"token function\">log</span><span class=\"token punctuation\">(</span>filtered<span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span></code></pre></div>\n</li>\n<li>What is a closure ?</li>\n<li>What is a Promise ?</li>\n<li>\n<p>What is the output ?</p>\n<div class=\"gatsby-highlight\" data-language=\"javascript\"><pre class=\"language-javascript\"><code class=\"language-javascript\"><span class=\"token keyword\">function</span> <span class=\"token function\">updateUserName</span><span class=\"token punctuation\">(</span><span class=\"token parameter\">user<span class=\"token punctuation\">,</span> name</span><span class=\"token punctuation\">)</span> <span class=\"token punctuation\">{</span>\nuser<span class=\"token punctuation\">.</span>name <span class=\"token operator\">=</span> name<span class=\"token punctuation\">;</span>\n<span class=\"token keyword\">return</span> user<span class=\"token punctuation\">;</span>\n<span class=\"token punctuation\">}</span>\n<span class=\"token keyword\">const</span> john <span class=\"token operator\">=</span> <span class=\"token punctuation\">{</span>\nname<span class=\"token operator\">:</span> <span class=\"token string\">'John'</span><span class=\"token punctuation\">,</span>\nage<span class=\"token operator\">:</span> <span class=\"token number\">48</span><span class=\"token punctuation\">,</span>\n<span class=\"token punctuation\">}</span><span class=\"token punctuation\">;</span>\nconsole<span class=\"token punctuation\">.</span><span class=\"token function\">log</span><span class=\"token punctuation\">(</span><span class=\"token string\">'John'</span><span class=\"token punctuation\">,</span> john<span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span>\n<span class=\"token keyword\">const</span> jane <span class=\"token operator\">=</span> <span class=\"token function\">updateUserName</span><span class=\"token punctuation\">(</span>john<span class=\"token punctuation\">,</span> <span class=\"token string\">'Jane'</span><span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span>\nconsole<span class=\"token punctuation\">.</span><span class=\"token function\">log</span><span class=\"token punctuation\">(</span><span class=\"token string\">'Jane'</span><span class=\"token punctuation\">,</span> jane<span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span>\nconsole<span class=\"token punctuation\">.</span><span class=\"token function\">log</span><span class=\"token punctuation\">(</span><span class=\"token string\">'John'</span><span class=\"token punctuation\">,</span> john<span class=\"token punctuation\">)</span><span class=\"token punctuation\">;</span></code></pre></div>\n</li>\n</ul>\n<p>⭐⭐⭐</p>\n<ul>\n<li>What is the event loop ?</li>\n</ul>","frontmatter":{"title":"JavaScript Interview questions","date":"August 15, 2020","description":"Basic interview questions"}}},"pageContext":{"slug":"/Interview/javascript/","previous":{"fields":{"slug":"/Interview/nodejs/"},"frontmatter":{"title":"Nodejs Backend Development questions","tags":["interview","backend"]}},"next":{"fields":{"slug":"/Interview/html/"},"frontmatter":{"title":"HTML Interview questions","tags":["interview","frontend"]}}}},"staticQueryHashes":["2841359383","3145232782"]}