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JS-Array-find-&-findIndex.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>JS Array find & findIndex</title>
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<body>
<h1>JS Array find & findIndex</h1>
<h1>Array find() Method</h1>
<p>
The Javascript <strong>arr.find()</strong> method in Javascript
is used to get the value of the first element in the array that satisfies
the provided condition. It checks all the elements of the array and
whichever the first element satisfies the condition is going to print.
This function will not work function having the empty array elements and
also does not change the original array.
</p>
<h3>Syntax:</h3>
<pre
class="language-javascript"
tabindex="0"
><code class="language-javascript">array<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">currentValue<span class="token punctuation">,</span> index<span class="token punctuation">,</span> arr</span><span class="token punctuation">)</span><span class="token punctuation">,</span>thisValue<span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>
<strong>Parameters:</strong> This method accepts 5 parameters as
mentioned above and described below:
</p>
<ul>
<li>
<strong>function:</strong> It is the function of the array that
works on each element.
</li>
<li>
<strong>currentValue:</strong> This parameter holds the current
element.
</li>
<li>
<strong>index:</strong> It is an optional parameter that holds the
index of the current element.
</li>
<li>
<strong>arr:</strong> It is an optional parameter that holds the
array object to which the current element belongs to.
</li>
<li>
<strong>thisValue:</strong> This parameter is optional. If a value
is to be passed to the function to be used as its “this” value else the
value “<strong>undefined</strong>” will be passed as its
“<strong>this</strong>” value.
</li>
</ul>
<p>
<strong>Return value:</strong> It returns the array element value if
any of the elements in the array satisfy the condition, otherwise it
returns undefined.<br />
</p>
<pre
class="language-markup"
tabindex="0"
><code class="language-markup"><span class="token doctype"><span class="token punctuation"><!</span><span class="token doctype-tag">DOCTYPE</span> <span class="token name">html</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>html</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>head</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>title</span><span class="token punctuation">></span></span>JavaScript<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>title</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>script</span><span class="token punctuation">></span></span><span class="token script"><span class="token language-javascript">
<span class="token keyword">var</span> ages <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">19</span><span class="token punctuation">,</span> <span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
document<span class="token punctuation">.</span><span class="token function">write</span><span class="token punctuation">(</span>ages <span class="token operator">+</span> <span class="token string">"<br>"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> ages<span class="token punctuation">.</span><span class="token function">find</span><span class="token punctuation">(</span>checkAdult<span class="token punctuation">)</span><span class="token punctuation">;</span>
document<span class="token punctuation">.</span><span class="token function">write</span><span class="token punctuation">(</span>b <span class="token operator">+</span> <span class="token string">"<br>"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">function</span> <span class="token function">checkAdult</span><span class="token punctuation">(</span><span class="token parameter">age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> age <span class="token operator">>=</span> <span class="token number">18</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>script</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>head</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>body</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>body</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>html</span><span class="token punctuation">></span></span></code></pre>
<hr />
<h3>Array findIndex() Method</h3>
<p>
The Javascript <strong>Array.findIndex()</strong> method is used
to return the first index of the element in a given array that satisfies
the provided testing function (passed in by the user while calling).
Otherwise, if no data is found then the value of -1 is returned.
</p>
<ul>
<li>
It does not execute the method once it finds an element satisfying the
testing method.
</li>
<li>It does not change the original array.</li>
</ul>
<h3>Syntax:</h3>
<pre
class="language-javascript"
tabindex="0"
><code class="language-javascript">array<span class="token punctuation">.</span><span class="token function">findIndex</span><span class="token punctuation">(</span><span class="token keyword">function</span><span class="token punctuation">(</span><span class="token parameter">currentValue<span class="token punctuation">,</span> index<span class="token punctuation">,</span> arr</span><span class="token punctuation">)</span><span class="token punctuation">,</span> thisValue<span class="token punctuation">)</span>
</code></pre>
<p>
<strong>Parameters:</strong> This method accepts five parameters as
mentioned above and described below:
</p>
<ul>
<li>
<strong>function:</strong> It is the function of the array that
works on each element.
</li>
<li>
<strong>currentValue:</strong> This parameter holds the current
element.
</li>
<li>
<strong>index:</strong> It is an optional parameter that holds the
index of the current element.
</li>
<li>
<strong>arr:</strong> It is an optional parameter that holds the
array object to which the current element belongs.
</li>
<li>
<strong>thisValue:</strong> This parameter is optional if a value
is to be passed to the function to be used as its “this” value else the
value “undefined” will be passed as its “this” value.
</li>
</ul>
<strong>Return value: </strong>
It returns the array element index if any of the elements in the array pass
the test, otherwise, it returns -1.
<br />
<pre
class="language-markup"
tabindex="0"
><code class="language-markup"><span class="token doctype"><span class="token punctuation"><!</span><span class="token doctype-tag">DOCTYPE</span> <span class="token name">html</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>html</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>head</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>title</span><span class="token punctuation">></span></span>JavaScript<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>title</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>script</span><span class="token punctuation">></span></span><span class="token script"><span class="token language-javascript">
<span class="token keyword">var</span> ages <span class="token operator">=</span> <span class="token punctuation">[</span><span class="token number">10</span><span class="token punctuation">,</span> <span class="token number">12</span><span class="token punctuation">,</span> <span class="token number">23</span><span class="token punctuation">,</span> <span class="token number">20</span><span class="token punctuation">]</span><span class="token punctuation">;</span>
document<span class="token punctuation">.</span><span class="token function">write</span><span class="token punctuation">(</span>ages <span class="token operator">+</span> <span class="token string">"<br><br>"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">var</span> b <span class="token operator">=</span> ages<span class="token punctuation">.</span><span class="token function">findIndex</span><span class="token punctuation">(</span>checkAdult<span class="token punctuation">)</span><span class="token punctuation">;</span>
document<span class="token punctuation">.</span><span class="token function">write</span><span class="token punctuation">(</span>b <span class="token operator">+</span> <span class="token string">"<br>"</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">function</span> <span class="token function">checkAdult</span><span class="token punctuation">(</span><span class="token parameter">age</span><span class="token punctuation">)</span> <span class="token punctuation">{</span>
<span class="token keyword">return</span> age <span class="token operator">>=</span> <span class="token number">18</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
</span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>script</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>head</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>body</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>body</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>html</span><span class="token punctuation">></span></span></code></pre>
<hr />
</body>
<script>
let ary = [2, 46, 48, 47, 45, 87, 4];
let b = ary.find(find);
function find(a) {
return a >= 18;
}
document.write(b + "<br>");
let ary2 = [50, 46, 48, 47, 45, 87, 4];
let b2 = ary.findIndex(find2);
function find2(a) {
return a >= 18;
}
document.write(b2);
</script>
</html>