get-this-to-work-4-this-works.js

function getThisToWork() {
	fetch('/wp-json/wp/v2/users/3', {
		method: 'GET',
		headers: {
			'Content-Type': 'application/json',
			'X-WP-Nonce': wpApiSettings.nonce, // replace with your nonce value
		},
	})
		.then(response => response.json())
		.then(data => {
			console.log(data)
			let incomingValue = JSON.parse(data.meta.list_of_associated_campaigns);
			let outGoingValue;

			console.log(incomingValue);
			console.log(typeof incomingValue);
			console.log(data);
            
            
            	if( Array.isArray(incomingValue)){
                  	incomingValue.push(post_ID.value);
                        outGoingValue = incomingValue;
                  }

			if (!Array.isArray(incomingValue) && incomingValue != undefined) {
				outGoingValue = Array(1).fill(incomingValue);
				console.log(outGoingValue);
			}
			if (incomingValue == "" || incomingValue == undefined) {
				console.log("Does not exist")

				let value = "New Value";
				outGoingValue = Array(1).fill(value);
				console.log(array);

			}
			if (incomingValue != "" && incomingValue != undefined) {
				data.meta.list_of_associated_campaigns = incomingValue;
				console.log(incomingValue)
				let array = Array(1).fill("New Value");
				console.log("Does exist")
			}

			console.log(incomingValue);

			const outGoingObject = JSON.stringify({
				meta: {
					list_of_associated_campaigns: JSON.stringify(outGoingValue)
				}
			});

			fetch('/wp-json/wp/v2/users/3', {
				method: 'POST',

				headers: {
					'Content-Type': 'application/json',
					'X-WP-Nonce': wpApiSettings.nonce, // replace with your nonce value
				},
				body: outGoingObject,
			}).then(response => response.json())
				.then(data => console.log(data))
		})
}


getThisToWork();