Multi tool use

Javascript “if” with “or” How check which will exec

if (a != 1 || b != 2) {
console.log(this, ' is required');
}


Can we get the answer a is required or b is required?

a is required

b is required

4 Answers
4

I am assuming this is what you want. If not, add more information.

function checkVariable(variable, value){
if(variable!=value) return variable+" is required";
}


There's no way to get the answer from variable that executed but I have another way to do.

var array = [{name:"a",value:2,checkvalue:1},{name:"b",value:3,checkvalue:2}];

for(var i = 0 ; i < array.length ; i++){
if(array[i].value!=array[i].checkvalue){
console.log(array[i].name + "is required!");
}
}


try this. I hope it can be adapted.

This would probably work, too:

const a = document.getElementById('a')
const b = document.getElementById('b')
let c;

function evaluateAB() {
c = "";
if((Number(a.value) != 1 && (c="a")) || (Number(b.value) != 2 && (c="b"))){
console.log(c ? c + ' is required' : void(0));
}
}

<label>a: <input type="number" value="0" id="a" /></label>
<label>b: <input type="number" value="0" id="b" /></label>
<button type="button" onclick="evaluateAB()">Evaluate</button>

When javascript short circuit that expression, it won't tell where, so you need to go over them, one-by-one.

If you have that many variables, I recommend to use an object instead, which would make it all so much easier, and you avoid pollute the environment with a bunch of variables.

When done like this, it is easy to expand, by simply add a new key/value pair, and pass cross different methods etc.

Stack snippet

// setup and init an object
var my_vars = {
"a": 0,
"b": 0,
"c": 0,
"d": 0
}

// assign its property values somewhere in your code
my_vars["a"] = 1;
my_vars["b"] = 2;
my_vars["d"] = 4;


// check which is missing
for (v in my_vars) {
if (my_vars[v] == 0) {
console.log(v, 'is required' );
}
}

a

b

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