how to call js function from php

1// The most basic method
2<?php
3echo '<script type="text/javascript">',
4     'someJsFunc();', // Or Whatever
5     '</script>';
6?>
7  
8// However, if what you are trying to achieve requires more complexity,
9// You might be better off adding the V8JS module, see link below

1<script>
2  var phpadd= <?php echo add(1,2);?> //call the php add function
3  var phpmult= <?php echo mult(1,2);?> //call the php mult function
4  var phpdivide= <?php echo divide(1,2);?> //call the php divide function
5</script>

1<?php
2 if(your condition){
3     echo "<script> window.onload = function() {
4     yourJavascriptFunction(param1, param2);
5 }; </script>";
6?>