var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];
var str = fruits.valueOf();
  
//输出结果: apple,peaches,oranges,mangoes

var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];
var str = fruits.join("|");
  
//print str: apple|peaches|oranges|mangoes

Click here to convert fruits array to CSV: 
<button onclick="javsacript:convert()">Convert to CSV</button>
<br>
<pre>var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];
</pre>
<script>
  function convert() {
    var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];
    var str = fruits.valueOf();
    alert(str);
}
</script>