图片预览

图片预览

/*
 * @param {string} fileId input标签id
 * @param {string} imageId img标签id
 * @param {number} maxSize 图片大小
 */
function imagePreview(fileId, imageId, maxSize) {
    var maxSize = maxSize || 1024 * 1024;
    var oFile = document.getElementById(fileId).files[0];
    var oImage = document.getElementById(imageId);
    var rFilter = /^(image/bmp|image/gif|image/jpeg|image/png|image/tiff)$/i;
    if (!oFile) {
        oImage.src = "";
        return;
    }
    if (!rFilter.test(oFile.type)) {
        alert("请选择图片");
        return;
    }
    if (oFile.size > maxSize) {
        alert("图片太大");
        return;
    }
    var oReader = new FileReader();
    oReader.onload = function(e) {
        oImage.src = e.target.result;
    };
    oReader.readAsDataURL(oFile);
}