I have a simple for loop below where I'm going through a specific property that has null values. I want to count the total of the nulls and store those in a variable, which should be 7. I keep converting the nulls to 0 or undefined.
const test = [
{
'theKey': null,
'theName': 'bill'
},
{
'theKey': null,
'theName': 'jon'
},
{
'theKey': null,
'theName': 'theo'
},
{
'theKey': null,
'theName': 'rich'
},
{
'theKey': null,
'theName': 'rigo'
},
{
'theKey': null,
'theName': 'cleo'
},
{
'theKey': null,
'theName': 'jill'
},
]
for (var i = 0; i < test.length; i++) {
const theValues = test[i]['theKey']
console.log(theValues)
}
I've tried...
console.log(theValues.length)
and
for (var i = 0; i < test.length; i++) {
const theValues = test[i]['theKey']
const theSum = _.sum(theValues)
// console.log(theValues)
console.log(theSum)
}
Using for-loop:
const test = [ { 'theKey': null, 'theName': 'bill' }, { 'theKey': null, 'theName': 'jon' }, { 'theKey': null, 'theName': 'theo' }, { 'theKey': null, 'theName': 'rich' }, { 'theKey': null, 'theName': 'rigo' }, { 'theKey': null, 'theName': 'cleo' }, { 'theKey': null, 'theName': 'jill' } ];
let count = 0;
for (var i = 0; i < test.length; i++) {
if (test[i]['theKey'] === null) {
count++;
}
}
console.log(count);Using Array#reduce:
const test = [ { 'theKey': null, 'theName': 'bill' }, { 'theKey': null, 'theName': 'jon' }, { 'theKey': null, 'theName': 'theo' }, { 'theKey': null, 'theName': 'rich' }, { 'theKey': null, 'theName': 'rigo' }, { 'theKey': null, 'theName': 'cleo' }, { 'theKey': null, 'theName': 'jill' } ];
const count = test.reduce((total, { theKey }) =>
theKey === null ? total + 1 : total
, 0);
console.log(count);theValues isn't an array, it doesn't have a length. It's also local to the for loop, so you can't access it after the loop.
There's no need for an array, just increment a counter variable.
let nullCount = 0;
for (let i = 0; i < test.length; i++) {
if (test[i].theKey === null) {
nullCount++;
}
}
console.log(nullCount);
const test = [
{
'theKey': null,
'theName': 'bill'
},
{
'theKey': null,
'theName': 'jon'
},
{
'theKey': null,
'theName': 'theo'
},
{
'theKey': null,
'theName': 'rich'
},
{
'theKey': null,
'theName': 'rigo'
},
{
'theKey': null,
'theName': 'cleo'
},
{
'theKey': null,
'theName': 'jill'
},
];
let count = 0;
for (var i = 0; i < test.length; i++) {
if(test[i]['theKey'] == null){
count++;
}
}
console.log(count);