27-Dec-2021

by cespinoza

JavaScript

let data = [{name: "eee"}, {name: "dan"}]
console.log(data[1].name)

let obj = {name: "pat", age: 11}
//console.log(obj.name)
//console.log(obj.age)

let myArray = [1,2,3]
//console.log(myArray.length)

// this is not a pragmatic approach
if (data[0].name.length == 0){
	alert("error");
}
if (data[1].name.length == 0){
	alert("error");
}

// using a for loop to check elements from an array
let data1 = [{name: "eee"}, {name: "dan"}]

for(var i=0; i<data1.length;i++){
	if (data[i].name==0){
  	console.log("error")
  }
}
// using other version of for loop 

let data2 = [{name: "eee"}, {name: "dan"}]
for(thing in data2){
	if (thing.name==0){
  	console.log("error")
  }
}

// looping and mutating elements into an array
// this is the only way to mutate all elements
// in place
let data3 = [{name: "eee"}, {name: "dan"}]
for(var i=0;i<data3.length;i++){
	data3[i].nameLength = data3[i].name.length
}

// homework
let data4 = [
	{name: "eee", results: [4,4.4,7]}, 
  {name: "dan", results: [6,5.4,3]}
]

for(var i=0;i<data4.length;i++){
 //data4[i].results
  
	let average = sum_of_all_elem_in_results/length_of_results
	data4[i].average = average
}