sumeru/sumeru/library/handlebars-helper.js

A Realtime Javascript RIA Framework For Mobile WebApp

var runnable = function(Handlebars){
	//foreach method
	Handlebars.registerHelper("foreach", function(context, options) {
	    var buffer = "", key;
	    if(context) {
	        if ( (context instanceof Array) ) {//数组的遍历
	            for(var i=0, j=context.length; i<j; i++) {
	                //如果是object类型，则，内容支持this，在解析的时候this会被直接被替换到到depth0上,
	                //因为this本身的方法不能依赖于使用object.value调用的方法，所以直接把key附到this上
	                // if ( 0 ) {
	                    // context[i].key = i;
	                    // buffer = buffer + options.fn(context[i]);
	                // } else {
	                    //解释一下，内容是字符串类型的，则不支持this，所以和object遍历一样，给它value选项
	                buffer += options.fn({
	                    key : i,
	                    index : i,
	                    value : context[i]
	                });
	                // }
	            }
	        }else if (typeof context ==='object'){//object的遍历
	            for (key in context) {
	                if (context.hasOwnProperty(key)) {
	                    buffer += options.fn({
	                        key : key,
	                        value : context[key]
	                    });
	                }
	            }
	        }else {
	            //did nothing。此方法只支持数组和对象，其他不支持
	        }
	    } else {
	        buffer = options.inverse(this);
	    }
	    return buffer;
	});
	
	
	/*
	 * 
	 * compare 
	 * 
	 * usage:
	 *
	 *{{#compare A ">" B}}  // (defaults to == if operator omitted)
	 *   when A < B
	 *{{else}}
	 *   when A >= B    
	 *{{/compare}}
	 * 
	 */    
	
	Handlebars.registerHelper('compare', function (lvalue, operator, rvalue, options) {
	
	    var operators, result;
	    
	    if (arguments.length < 3) {
	        throw new Error("Handlerbars Helper 'compare' needs 2 parameters");
	    }
	    
	    if (options === undefined) {
	        options = rvalue;
	        rvalue = operator;
	        operator = "===";
	    }
	    
	    operators = {
	        '==': function (l, r) { return l == r; },
	        '===': function (l, r) { return l === r; },
	        '!=': function (l, r) { return l != r; },
	        '!==': function (l, r) { return l !== r; },
	        '<': function (l, r) { return l < r; },
	        '>': function (l, r) { return l > r; },
	        '<=': function (l, r) { return l <= r; },
	        '>=': function (l, r) { return l >= r; },
	        'typeof': function (l, r) { return typeof l == r; }
	    };
	    
	    if (!operators[operator]) {
	        throw new Error("Handlerbars Helper 'compare' doesn't know the operator " + operator);
	    }
	    
	    result = operators[operator](lvalue, rvalue);
	    
	    if (result) {
	        return options.fn(this);
	    } else {
	        return options.inverse(this);
	    }
	
	});
	
}

if(typeof module !='undefined' && module.exports){
	module.exports = runnable;
}else{
    runnable(Handlebars);
}