Javascript/Jquery Convert string to array

Question

i have a string

var traingIds = "${triningIdArray}"; // ${triningIdArray} this value getting from server 
alert(traingIds) // alerts [1,2]
var type = typeof(traingIds ) 
alert(type) // // alerts String

now i want to convert this to array so that i can iterate

i tried

var trainindIdArray = traingIds.split(',');
$.each(trainindIdArray, function(index, value) { 
 alert(index + ': ' + value); // alerts 0:[1 , and 1:2]
});

how to resolve this?

Answer 1

Since array literal notation is still valid JSON, you can use JSON.parse() to convert that string into an array, and from there, use it's values.

var test = "[1,2]";
parsedTest = JSON.parse(test); //an array [1,2]
//access like and array
console.log(parsedTest[0]); //1
console.log(parsedTest[1]); //2

• Watercayman: Wow, this is just brilliant... and simple Thank you.
• KuboMD: I have input just like OPs, except the var is set to the .attr() of my element. It has typeof string and looks like "['foo','bar']". When I try JSON.parse i get the Uncaught SyntaxError: Unexpected token ' in JSON at position 1 at JSON.parse (<anonymous>) error. Any idea?

Answer 2

Change

var trainindIdArray = traingIds.split(',');

to

var trainindIdArray = traingIds.replace("[","").replace("]","").split(',');

That will basically remove [ and ] and then split the string

Answer 3

Assuming, as seems to be the case, ${triningIdArray} is a server-side placeholder that is replaced with JS array-literal syntax, just lose the quotes. So:

var traingIds = ${triningIdArray};

not

var traingIds = "${triningIdArray}";

Answer 4

check this out :)

var traingIds = "[1,2]"; // ${triningIdArray} this value getting from server 
alert(traingIds); // alerts [1,2]
var type = typeof(traingIds);
alert(type); // // alerts String
//remove square brackets
traingIds = traingIds.replace('[','');
traingIds = traingIds.replace(']','');
alert(traingIds); // alerts 1,2 
var trainindIdArray = traingIds.split(',');
​for(i = 0; i< trainindIdArray.length; i++){
 alert(trainindIdArray[i]); //outputs individual numbers in array
 }​ 

• KC S: You can use eval. eg. eval("[1,2]") # => [1,2]
• Young Emil: It surprises me @Sam Kah Chiin 's comment is not an answer. It really a great deal to this question. it is single lined and simple. Thanks
• KC S: @YoungMillie, actually using eval in javascript can be dangerous as improper use of eval opens up your code for injection attacks. Check this stackoverflow :)
• Young Emil: Thanks @Sam Kah Chiin , knowledge is power. I now understand what eval is and how dangerous it can be.
• Young Emil: Then in that case...I guess @Clayton 's answer is also a good way around the problem.

Answer 5

There are four ways to convert a string into an array in JavaScript. Here you have code examples on how they look.

Example Code:

let string = "Javascript";

First Method:

let array = [string];

Second Method:

let array = [...string];

Third Method:

let array = Array.from(string); 

Fourth Method:

let array = string.split('');

I hope that my answer helps you!