How to Make Character Jump OnPress of Button

An example would be...

var run:Boolean = true;

var runSpeed:Number = 5;

var jumping:Boolean = false;

var jumpSpeedLimit:int = 10;

var jumpSpeed:Number = 0;

jump_btn.addEventListener(MouseEvent.CLICK, jump);

function jump(event:MouseEvent):void

{

    mainJump();

}

character.addEventListener(Event.ENTER_FRAME, moveCharacter);

function moveCharacter(event:Event):void{

    if(run){

        character.x += runSpeed;

    }

    if(jumping){

        mainJump();

    }

}

function mainJump():void{

    if(!jumping){

        jumping = true;

        jumpSpeed = jumpSpeedLimit*-1;

        character.y += jumpSpeed;

    } else {

        if(jumpSpeed < 0){

            jumpSpeed *= 1 - jumpSpeedLimit/75;

            if(jumpSpeed > -jumpSpeedLimit/5){

                jumpSpeed *= -1;

            }

        }

        if(jumpSpeed > 0 && jumpSpeed <= jumpSpeedLimit){

            jumpSpeed *= 1 + jumpSpeedLimit/50;

        }

        character.y += jumpSpeed;

        if(character.y >= stage.stageHeight - character.height){

            jumping = false;

            character.y = stage.stageHeight - character.height;

        }

    }

}