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Accepted
Eduardo Sebastian
Asked: 2020-09-06 08:10:13 +0800 CST 2020-09-06 08:10:13 +0800 CST

Find variables in a document

  • 772

var a1 = setTimeout(function(){});
var a2 = setTimeout(function(){});
var a3 = setTimeout(function(){});
var a4 = setTimeout(function(){});
var a5 = setTimeout(function(){});

if(){
clearInterval(a1);
clearInterval(a2);
// etc..
}

If I had many in a code setTimeout, and each of these starts with a variable called "a" + un número, how could I identify all the variables that start with a and then with a number, in order to put them in an array and go through them to apply the clearInterval, instead of doing el clearIntervalto each of them (imagining that there are more than 50 variables would be very tedious).

javascript

4 Answers

  1. In general, any declared global variable is an attribute of the object window:

    var a1 = 5;
var a2 = 6;
var a3 = 'hola';

let i = 1;

while(window['a' + i]) {
  console.log('La variable a' + i + ' vale ' + window['a' + i]);
  i++;
}

    But this doesn't work with local variables even when the context is window:

    (function () {
  var a1 = 5
  var a2 = 6
  var a3 = 'hola'

  let i = 1;

  while(window['a' + i]) {
    console.log('La variable a' + i + ' vale ' + window['a' + i]);
    i++;
  }
  
  console.log('El contexto es: ', this.toString());
})()

    My recommendation is to store the values ​​directly in an array:

    let timeouts = [];

for (let i = 0;i < 5; i++) {
  timeouts.push(setTimeout(() => console.log('Hola ' + i), i * 2000));
  // Al usar let en lugar de var, cada callback tiene un valor distinto para i ;)
}

setTimeout(() => {
  timeouts.forEach(id => clearTimeout(id));
//clearTimeout en el caso presente, no clearInterval
  console.log('Eliminados los timeouts no ejecutados');
}, 3000)

    • 13
  2. Best Answer

    With the function Object.keys(window)you can get all the objects.

    Example:

    <!DOCTYPE html>
<html lang="en">
<head>
	<script>
		var a1 =  setInterval(function(){console.log("txt1");},1000);
		var a2 =  setInterval(function(){console.log("txt2");},1000);
		var a3 =  setInterval(function(){console.log("txt3");},1000);
		var a4 =  setInterval(function(){console.log("txt4");},1000);
		var a5 =  setInterval(function(){console.log("txt5");},1000);

		function detenerObjetosInterval(){
            //obteniendo objetos
			var objetosTodos=Object.keys(window);
			var objetosInterval=[];
			//obteniendo objetos que inicia con 'a'
			for(i = 0 ; i < objetosTodos.length ; i++){
				if(objetosTodos[i].indexOf('a')==0){
					objetosInterval.push(objetosTodos[i]);
				}
			}
			//deteniendo objetos
			for(i = 0 ; i < objetosInterval.length ; i++){
				clearInterval(eval(objetosInterval[i]));
			}
		}
		
		//detener intervals despues de 5 seg
		setTimeout(function(){
			console.log("deteniendo intervals");
			detenerObjetosInterval();
		},5000);
	</script>
</head>
<body>
</body>
</html>

    I recommend that the var start with a more compound word (eg var aInterval = .... ), because if you use libraries or other things you could take other objects

    • 4

  3. I would do the following: create an array with the names of all possible variables, then iterate through it with forEachcheck if the object windowhas a "property" named as the variable in the array, if so, do whatever I need to do with it variable, if not, I show an error saying that said variable does not exist, example:

    var a1 = setTimeout(() => {});
var a2 = setTimeout(() => {});
var a3 = setTimeout(() => {});
var a4 = setTimeout(() => {});
var a5 = setTimeout(() => {});

const possibleVariablesNum = 10;
var possibleVariablesArr = [];

for(var i = 0; i <= possibleVariablesNum; i++){
  possibleVariablesArr.push("a" + i.toString());
}

possibleVariablesArr.forEach((value, index) => {
  if (window.hasOwnProperty(value)) {
    console.log("La variable " + value + " existe y se limpiará");
    clearInterval(window[value]);
  }else{
    console.error("La variable " + value + " NO existe");
  }
})

    • 1

  4. You can store the identifiers of setTimeoutand setIntervalin an object as follows:

    let itervals = {
    a1: setInterval(()=>{}, 100),
    a2: setInterval(()=>{}, 100),
    a3: setInterval(()=>{}, 100)
}

    Then, you can loop through the object:

    for(let i in intervals){
    clearInterval(intervals[i]);
}

    I propose to use an object because variables are declared in your code, but you can also use a Arraysimple:

    let intervals = [
    setInterval(()=>{}, 100),
    setInterval(()=>{}, 100),
    setInterval(()=>{}, 100),
]

for(let i in intervals){
    clearInterval(intervals[i]);
}
    • 1