JQuery to Native Javascript (simple click call function) -

i'm trying convert following jquery native javascript, can't seem work.

any appreciated.

jquery:

$(document).ready(function() {   $("button").click(function() {     var char = "0123456789abcdefghijklmnopqrstuvwxyz";     var fullchar = "0123456789abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";     var genhash = "";     var i;      (i = 0; < 8; i++) {       var rnum = math.floor(math.random() * char.length);       genhash += char.substring(rnum, rnum + 1);     }      $("input").val(genhash);   }).click(); }); 

native javascript:

function passwordgenerator() {     var char = "0123456789abcdefghijklmnopqrstuvwxyz";   var fullchar = "0123456789abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";   var genhash = "";   var i;    (i = 0; < 8; i++) {     var rnum = math.floor(math.random() * char.length);     genhash += char.substring(rnum, rnum + 1);   }    document.getelementsbytagname("input").value = genhash; }  document.getelementsbytagname("button").onclick = function() {   passwordgenerator(); }; passwordgenerator(); 

function passwordgenerator() {      var char = "0123456789abcdefghijklmnopqrstuvwxyz";    var fullchar = "0123456789abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";    var genhash = "";    var i;      (i = 0; < 8; i++) {      var rnum = math.floor(math.random() * char.length);      genhash += char.substring(rnum, rnum + 1);    }      document.getelementsbytagname("input").value = genhash;  }    document.getelementsbytagname("button").onclick = function() {    passwordgenerator();  };  passwordgenerator();

<input type="text" />  <button>    generate password  </button>

try adding index [0] of element within htmlcollection returned document.getelementsbytagname()

function passwordgenerator() {    var char = "0123456789abcdefghijklmnopqrstuvwxyz";    var fullchar = "0123456789abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz";    var genhash = "";    var i;      (i = 0; < 8; i++) {      var rnum = math.floor(math.random() * char.length);      genhash += char.substring(rnum, rnum + 1);    }    // add index `[0]` of element within `htmlcollection` after call    // `.getelementsbytagname("input")`    document.getelementsbytagname("input")[0].value = genhash;  }  // add index `[0]` of element within `htmlcollection` after call  // `.getelementsbytagname("button")`  var button = document.getelementsbytagname("button")[0];  button.addeventlistener("click", function() {    passwordgenerator();  });  // call `click` event on `button`  button.click();

<input type="text" />  <button>    generate password  </button>