使用js怎么将网页放大与缩小方法

function exitFull() {
    // 判断各种浏览器，找到正确的方法
    var exitMethod = document.exitFullscreen || //W3C
        document.mozCancelFullScreen || //Chrome等
        document.webkitExitFullscreen || //FireFox
        document.webkitExitFullscreen; //IE11
    if (exitMethod) {
        exitMethod.call(document);
    } else if (typeof window.ActiveXObject !== "undefined") { //for Internet Explorer
        var wscript = new ActiveXObject("WScript.Shell");
        if (wscript !== null) {
            wscript.SendKeys("{F11}");
        }
    }
}

function requestFullScreen(element) {
    // 判断各种浏览器，找到正确的方法
    var requestMethod = element.requestFullScreen || //W3C
        element.webkitRequestFullScreen ||    //Chrome等
        element.mozRequestFullScreen || //FireFox
        element.msRequestFullScreen; //IE11
    if (requestMethod) {
        requestMethod.call(element);
    }
    else if (typeof window.ActiveXObject !== "undefined") {//for Internet Explorer
        var wscript = new ActiveXObject("WScript.Shell");
        if (wscript !== null) {
            wscript.SendKeys("{F11}");
        }
    }
}