JavaScript中數組函數array()的相關介紹

在程式語言中陣列的重要性不言而喻，JavaScript中陣列也是最常使用的物件之一，陣列是值的有序集合，由於弱型別的原因，JavaScript中陣列十分靈活、強大，不像是Java等強型別高階語言陣列只能存放相同型別或其子型元素，JavaScript在同一個陣列中可以存放多種型別的元素，而且是長度也是可以動態調整的，可以隨著資料增加或減少自動對數組長度做更改。

Array()是一個用來建構陣列的內建建構器函數。陣列主要由以下三種建立方式：

<span class="pln">array </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Array</span><span class="pun">()</span><br/><span class="pln">array </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Array</span><span class="pun">([</span><span class="pln">size</span><span class="pun">])</span><span class="pln">array </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Array</span><span class="pun">(</span><span class="pln">element0</span><span class="pun">,</span><span class="pln"> element1</span><span class="pun">,</span><span class="pln"> </span><span class="pun">...,</span><span class="pln"> elementN</span><span class="pun">)</span>

參數

參數 size 是期望的陣列元素個數。傳回的數組，length 欄位將被設為 size 的值。

參數 element ..., elementn 是參數列表。當使用這些參數來呼叫建構函式 Array() 時，新建立的陣列的元素就會被初始化為這些值。它的 length 欄位也會被設定為參數的個數。

傳回值

傳回新建立並被初始化了的陣列。

如果呼叫建構函式 Array() 時沒有使用參數，那麼傳回的陣列為空，length 欄位為 0。

當呼叫建構函式時只傳遞給它一個數字參數，該建構函式會傳回具有指定個數、元素為 undefined 的陣列。

當其他參數呼叫 Array() 時，此建構函式將以參數指定的值初始化陣列。

當把建構函式當作函式調用，不使用 new 運算子時，它的行為與使用 new 運算子呼叫它時的行為完全一樣。

Array 物件方法

Array 物件屬性

concat()方法：

合併陣列

[1,2]concat([3,4],[5,6]);//[1,2,3,4,5,6]

join()方法：

<span class="tag"><script</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text/javascript"</span><span class="tag">></span><br/><span class="pln"> </span><span class="kwd">var</span><span class="pln"> a </span><span class="pun">=</span><span class="pln"> </span><span class="pun">[</span><span class="lit">1</span><span class="pun">,</span><span class="lit">2</span><span class="pun">,</span><span class="lit">3</span><span class="pun">];</span><br/><span class="pln"> a</span><span class="pun">.</span><span class="pln">join</span><span class="pun">(</span><span class="str">""</span><span class="pun">);</span><span class="com">// =>"123"</span><span class="tag"></script></span>

#pop()方法：

移除陣列最後一個元素，並將其傳回

<span class="tag"><script</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text/javascript"</span><span class="tag">></span><br/><span class="pln"> </span><span class="kwd">var</span><span class="pln"> fruits </span><span class="pun">=</span><span class="pln"> </span><span class="pun">[</span><span class="str">"apple"</span><span class="pun">,</span><span class="str">"banana"</span><span class="pun">,</span><span class="str">"pineapple"</span><span class="pun">];</span><br/><span class="pln"> fruits</span><span class="pun">.</span><span class="pln">pop</span><span class="pun">();</span><span class="com">// pineapple </span><br/><span class="pln"> console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="pln">fruits</span><span class="pun">);</span><span class="com">//["apple","banana"]</span><span class="tag"></script></span>

shift()方法：

刪除並傳回陣列的第一個元素。

<span class="tag"><script</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text/javascript"</span><span class="tag">></span><br/><span class="pln"> </span><span class="kwd">var</span><span class="pln"> a </span><span class="pun">=</span><span class="pln"> </span><span class="pun">[</span><span class="lit">1</span><span class="pun">,</span><span class="lit">2</span><span class="pun">,</span><span class="lit">3</span><span class="pun">];</span><br/><span class="pln"> a</span><span class="pun">.</span><span class="pln">shift</span><span class="pun">();</span><span class="com">//1</span><br/><span class="pln"> console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="pln">a</span><span class="pun">);</span><span class="com">//[2,3]</span><span class="tag"></script></span>

slice(start,end)

方法：截取陣列的某一部分，不會對原始陣列進行任何修改。

<span class="tag"><script</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text/javascript"</span><span class="tag">></span><br/><span class="pln">  </span><span class="kwd">var</span><span class="pln"> num </span><span class="pun">=</span><span class="pln"> </span><span class="pun">[</span><span class="str">"a"</span><span class="pun">,</span><span class="str">"b"</span><span class="pun">,</span><span class="str">"c"</span><span class="pun">,</span><span class="str">"d"</span><span class="pun">,</span><span class="str">"e"</span><span class="pun">];</span><br/><span class="pln">  console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="pln">num</span><span class="pun">.</span><span class="pln">slice</span><span class="pun">(</span><span class="lit">1</span><span class="pun">,</span><span class="lit">4</span><span class="pun">));</span><span class="com">//["b","c","d"]</span><br/><span class="pln">  console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="pln">num</span><span class="pun">);</span><span class="com">//["a","b","c","d","e"]</span><span class="tag"></script></span>

splice(start,delete_count,i1,i2…)

方法：刪除陣列元素的同時新增新的元素。 i1,i2為要插入的新元素

<span class="tag"><script</span><span class="pln"> </span><span class="atn">type</span><span class="pun">=</span><span class="atv">"text/javascript"</span><span class="tag">></span><br/><span class="pln"> </span><span class="kwd">var</span><span class="pln"> arr </span><span class="pun">=</span><span class="pln"> </span><span class="pun">[</span><span class="str">"js"</span><span class="pun">,</span><span class="str">"css"</span><span class="pun">,</span><span class="str">"html"</span><span class="pun">,</span><span class="str">"php"</span><span class="pun">,</span><span class="str">"c"</span><span class="pun">];</span><br/><span class="pln"> arr</span><span class="pun">.</span><span class="pln">splice</span><span class="pun">(</span><span class="lit">1</span><span class="pun">,</span><span class="pln"> </span><span class="lit">2</span><span class="pun">,</span><span class="str">"python"</span><span class="pun">,</span><span class="str">"jquery"</span><span class="pun">);</span><span class="com">//["css","html"]</span><br/><span class="pln"> console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="pln">arr</span><span class="pun">);</span><span class="com">//["js","python","jquery""php","c"]</span><span class="tag"></script</span>

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