如何检查数组Javascript中是否存在字符串或数字

Question

I have a functions which asks the users to write their favorites animals ant then stores it in an array called animals.When a user executes the function I want to check if the animal he wants is inside the array and if yes to show the index of the animal(for example:The animal you entered is already in the array.Its index number is...).Any ideas?

var animals=[]
function anim(){
var ani=prompt("Give me an animal you like");
animals.push(ani);

}

Answer 1

You can iterate across the array and with regex to get accurate result regard less input case

 function searchArr(arr, q){      
      for (i = 0; i < arr.length; i++){
        patt = new RegExp(q,"i");
        if (patt.test(arr[i])) return i;
      }
      return false;
    }

Testing Code:

 animals = new Array('dog', 'cat', 'camel', 'deer');
    q = prompt("Enter Animal Name");
    r = searchArr(animals,q);
    alert(r)
    if (r || r ===0){
      alert("Animal found and its index " + r)
    }
    else{
      alert("Not found")
    }

Demo: http://jsbin.com/jolaqiduka/1/

Answer 2

you can find out if a value is inside of an array by using indexOf() .

for example: animals.indexOf('dog');

this will return the index of the string 'dog'. if it doesn't exist, it will return a value of -1.

Answer 3

var animals= new Array('dog');
var ani=prompt("Give me an animal you like");
if(animals.indexOf(ani) >= 0 ){
    alert(animals.indexOf(ani));


}else{
   animals.push(ani);
}

JsFillde Demo

Answer 4

This this way

var animals=[]

function anim() {
   var ani = prompt("Give me an animal you like");

   // The function returns a position of an input element (in array) begins from the 0
   // or -1 if the element is not exists in the array
   if (animals.indexOf(ani) > -1)
       alert('Already in');
   else
       animals.push(ani);
}

Next fiddle may help: http://jsfiddle.net/8g5gpqx2/