How do I add push a new object into the array if it doesn't exist?
I check this link: How to check if array element exists or not in javascript?
but not sure how to push the new object though!
var element = [];
element['obj'] = 'one';
if (typeof element['obj']['bg'] === 'undefined') {
console.log('not defined');
element['obj']['bg'] = 'red';
console.log(element);
} else {
console.log('defined');
}var element = []; defines an array and not an object. To push a new value into an array you need to use the push method :
element.push({'obj' : 'one'});
But I think you do not need to create an array here, but just create an object. Declare your object like var element = {};
Like this the line element['obj'] = 'one'; works, you have an object with the key obj and the value one.
When you write element['obj']['bg'] you try to access on an object inside an object. So before set the value red into you need create the object :
element['obj'] = {};
element['obj']['bg'] = 'red';
Full example :
var element = {};
element['obj'] = {};
if (typeof element['obj']['bg'] === 'undefined') {
console.log('not defined');
element['obj']['bg'] = 'red';
console.log(element);
} else {
console.log('defined');
}The element is of type string, not an object or an array.
Change the particular variable to an array:
var element = {};
element['obj'] = ['one'];
if ( typeof element['obj']['bg'] === 'undefined' ) {
console.log('not defined');
element['obj']['bg'] = 'red';
console.log(element);
} else {
console.log('defined');
}
Or better an object:
element['obj'] = {};
element['obj']['id'] = 'one';
The string objects are immutable objects.
bg on an array is a good practice? Maybe we should wait OP to explain about what structure he expect.
:)Try inserting an empty array beforehand;
var element = [];
element['obj'] = 'one';
if ( typeof element['obj']['bg'] === 'undefined' ) {
console.log('not defined');
element['obj'] = [element['obj']];
element['obj']['bg'] = 'red';
console.log( element);
} else {
console.log('defined');
}
var element = [];
element['obj'] = 'one';
if ( typeof element['obj']['bg'] === 'undefined' ) {
console.log('not defined');
element['obj'] = {'bg':'red'};
console.log("My value:"+element['obj']['bg'] );
} else {
console.log('defined');
}
You could try this way.
var element = [],item = [];
item['obj'] = 'one';
element.push(item);
if ( typeof element['obj']['bg'] === 'undefined' ) {
console.log('not defined');
item['bg']='red';
element.push(item);
console.log( element);
} else {
console.log('defined');
}
element.push({'bg':'red'});? It's a bit unclear what you're asking. Could you be more specific?element['obj'] = 'one';--> this initialiseselement['obj']to string, and then you want to add a key/value pair to that (string)?arrayorobject?element['obj'] = 'one';create attrobjonelement, but its not account to length.element['obj'] = 'one', when you doelement['obj']['bg'] === 'undefined'it's equals to'one'['bg']. I think It has no sense.