constructing two dimensional array dynamically

Question

I have some values in JavaScript array as shown

var sampledata = {10,20,30,40};// these values would come from database later

I want to create a two dimensional array with these values.

I want to create a array as

var newData = [[0,10],[1,20],[2,30],[3,40]]

• Felipe: The sample data syntax is invalid. Also, i don't understand what you're trying to achieve.
• Chandu: Do you mean var sampledata = [10,20,30,40];

Answer 1

Pure JavaScript:

var newData = [];
var sampledata = [10,20,30,40];
for (var i = 0; i < sampledata.length; i++) {
 newData.push([i, sampledata[i]]);
}

Using higher-order functions:

var newData = sampledata.map(function(el, i) {
 return [i, el];
})

• Yanick Rochon: your JQuery example needs to return [[i, el]] or it will add two items instead of a nested array of two items.
• Wayne: @Yanick - I don't have a jQuery example. If you're talking about the example that uses map then, no, it should not return [[i, el]]. The function given to map should return elements of newData, which are one-dimensional arrays.
• Yanick Rochon: my mistake. I don't know why, but when I tried the first time on jsfiddle.net, I got [0,10,1,20,2,30,...]. I cannot reproduce this, so I assume it must have been my fault, or something else...

Answer 2

if sampledata is an array

var sampledata = [10,20,30,40]
var newData = []
jQuery.each(sampledata,function(i,data){newData.push([i,data])})

• Kiran: Thank you Naren Sisodiya , i have tried for(var i=0li<sampledata.length;i++) {newData.push([i,data]) its not working , are they both same ??
• Wayne: @Kiran - Use sampledata[i] where you currently have data. See my answer for a full example.
• Naren Sisodiya: look at lwburk's response for plain javascript, I've used jQuery