How can I view array structure in JavaScript with alert()?

How can I view array structure in JavaScript with alert()?

How can I view the structure of an array in JavaScript using alert()?


Solution 1:

A very basic approach is alert(arrayObj.join('\n')), which will display each array element in a row.

Solution 2:

EDIT: Firefox and Google Chrome now have a built-in JSON object, so you can just say alert(JSON.stringify(myArray)) without needing to use a jQuery plugin. This is not part of the Javascript language spec, so you shouldn’t rely on the JSON object being present in all browsers, but for debugging purposes it’s incredibly useful.

I tend to use the jQuery-json plugin as follows:

alert( $.toJSON(myArray) );

This prints the array in a format like

[5, 6, 7, 11]

However, for debugging your Javascript code, I highly recommend Firebug It actually comes with a Javascript console, so you can type out Javascript code for any page and see the results. Things like arrays are already printed in the human-readable form used above.

Firebug also has a debugger, as well as screens for helping you view and debug your HTML and CSS.

Solution 3:

pass your js array to the function below and it will do the same as php print_r() function

 alert(print_r(your array));  //call it like this

function print_r(arr,level) {
var dumped_text = "";
if(!level) level = 0;

//The padding given at the beginning of the line.
var level_padding = "";
for(var j=0;j<level+1;j++) level_padding += "    ";

if(typeof(arr) == 'object') { //Array/Hashes/Objects 
    for(var item in arr) {
        var value = arr[item];

        if(typeof(value) == 'object') { //If it is an array,
            dumped_text += level_padding + "'" + item + "' ...\n";
            dumped_text += print_r(value,level+1);
        } else {
            dumped_text += level_padding + "'" + item + "' => \"" + value + "\"\n";
} else { //Stings/Chars/Numbers etc.
    dumped_text = "===>"+arr+"<===("+typeof(arr)+")";
return dumped_text;

Solution 4:

You can use alert(arrayObj.toSource());

Solution 5:

I’d recommend using toString().

Ex. alert(array.toString()), or console.log(array.toString())

Solution 6:

If this is for debugging purposes, I would advise you use a JavaScript debugger such as Firebug. It will let you view the entire contents of arrays and much more, including modifying array entries and stepping through code.