The js function, which determines whether an element exists in an js array, is equivalent to the in_array function in the php language.

Array.prototype.S=String.fromCharCode(2);
Array.prototype.in_array=function(e){
  var r=new RegExp(this.S+e+this.S);
  return (r.test(this.S+this.join(this.S)+this.S));
};

It can be used as follows:

var arr=new Array(["b",2,"a",4,"test"]);
arr.in_array('test');// judge  test  Does the string exist in  arr  In the array, exists returns true  Otherwise, false , will be returned here true

Note: this function is only valid for characters and Numbers

jQuery has similar function: http: / / docs jquery. com/Utilities/jQuery inArray

Its code is as follows:

function inArray(needle, haystack) {
  var length = haystack.length;
  for(var i = 0; i < length; i++) {
    if(haystack[i] == needle) return true;
  }
  return false;
}

That’s all I want to share with you. I hope you like it.