After ordering the code to return an Alert if the input values are reset, when pressing the button the page hangs

Question

When the values of the inputs are zeroed, the right one was to appear a alert and a change in the div, but the page hangs and I can no longer put numbers or click the button.

I realized that when I take the .lenght the code works.

Why the lenght hangs the page?

function tabuada(){
let ini=document.getElementById('txt1')
let fim=document.getElementById('txt2')
let passo=document.getElementById('txt3')
let res=document.getElementById('res')

if (ini.value.lenght== 0 || fim.value.lenght== 0 || passo.value.lenght== 0){
    window.alert('[ERRO], dados faltando...')
    res.innerHTML='Impossível de contar...'
}
else{
    res.innerHTML='Contando:'
    let i=Number(ini.value)
    let f=Number(fim.value)
    let p=Number(passo.value)
if(i<f){
    //Contagem Crescente
    for(let c=i; c<=f; c += p){
        res.innerHTML+=`${c}\u{1F449}`
    }
        res.innerHTML+=`\u{1F3C1}`
}
else{
    //Contagem Regressiva
    for(let c=i; c>=f; c-=p){
        res.innerHTML+=`${c}\u{1F449}`
    }
        res.innerHTML+=`\u{1F3C1}`
}
}
}

Answer 1

In the if you use ini.value.length. This is not possible for inputs as inputs do not have length. The elements are the ones you assigned in the variables in document.getElementByID, that cannot be used in the way you reported in the question, IN THIS CASE.

In your case, as you said you are using inputs, then you must use value.

You mentioned that you want to check if the field is 'zeroed'. I don’t understand if you mean if the field has 0 (zero) or if the field is empty ("").

I will make an example with the two options for you to observe.

• If your case is if the field has 0 (zero):

if (ini.value == 0 || fim.value == 0 || passo.value == 0) {
  //Sua condição aqui
}

• Now if your case is if the field is empty (""):

if (ini.value == "" || fim.value == "" || passo.value == "") {
  //Sua condição aqui
}