buffer 必须返回 function，它返回 String，这是我通过调用 buffer('Hello') 创建的
/**
* Function makeBuffer
* @returns {String}
*/
function makeBuffer() {
let str = '';
return function(...rest) {
if (rest.length === 0) {
return str;
}
str += rest;
str.toString();
};
};
/**
* Starting unit-test
* @returns {String}
*/
;(function () {
let buffer;
beforeEach(function() {
buffer = makeBuffer();
});
it("returns String", function() {
buffer(null);
buffer(false);
assert.equal(buffer(), "nullfalse");
});
})()
var buffer = makeBuffer();
buffer('Hello');
buffer(' my');
buffer(' world');
console.log(buffer());<html>
<head>
<meta charset="utf-8">
<script src="https://js.cx/test/libs.js"></script>
</head>
<body>
</body>
</html>最佳答案
那是因为
[null].toString() == ""
[false].toString() == "false"
尝试
function makeBuffer() {
let str = '';
return function(...rest) {
if (rest.length === 0) {
return str;
}
str += rest.map(e => { return "" + e }).join("");
};
};
关于javascript - 为什么输出中没有出现字符串 "nullfalse"？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44199788/