How to convert Javascript Arrays to CSV (Comma separated values)

文章源自:http://viralpatel.net/blogs/convert-javascript-arrays-to-csv/

How to convert Javascript Arrays to CSV (Comma separated values)

Let’s see a small code snippet in Javascript that converts JS arrays in Comma separated values. It is also possible to convert an array to delimited text where one can choose the separator.

var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];

var str = fruits.toString();

//print str: apple, peaches, oranges, mangoes

 

The toString() method converts an array into a String and returns the result. The returned string will separate the elements in the array with commas.

That’s simple. Javascript Array also has method valueOf() that does the same thing.

var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];

var str = fruits.valueOf();

//print str: apple,peaches,oranges,mangoes

 

The valueOf() method returns the primitive value of an array. Again the returned string will separate the elements in the array with commas.

There is no difference in toString() and valueOf(). Try with different data types like number, strings etc it would give the same result.

Also sometimes one wants to create delimited string from an array. Lets say pipe (|) separated string!. In such cases Arrays join() method comes quite handy. The join() method joins the elements of an array into a string, and returns the string.

By default the join() method returns a comma (,) separated value of the array. But you can give argument to join() method and specify the separator. For example:

var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];

var str = fruits.join("|");

//print str: apple|peaches|oranges|mangoes

 

How to convert CSV to Array in Javascript

Let us see how to convert a string with commas in it into an Array. Consider following case:

var fruits = ['apple', 'peaches', 'oranges', 'mangoes'];

var str = "apple, peaches, oranges, mangoes";

var fruitsArray = str.split(",");

//print fruitsArray[0]: apple

 Thus split() method of String comes handy for this. It is used to split a string into an array of substrings, and returns the new array. The split() method does not change the original string. Check the sytax of split() method.

string.split(separator,limit)

 

• separator (Optional). Specifies the character, or the regular expression, to use for splitting the string. If omitted, the entire string will be returned (an array with only one item
• limit (Optional). An integer that specifies the number of splits, items after the split limit will not be included in the array

Note: If an empty string (“”) is used as the separator, the string is split between each character. Thus:

var str="How are you doing today?";
var n=str.split("");

 The result of n will be an array with the values:

H,o,w, ,a,r,e, ,y,o,u, ,d,o,i,n,g, ,t,o,d,a,y,?