TypeScript/JavaScript forEach call
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TypeScript/JavaScript forEach call
提问by pitosalas
I am having trouble understanding this bit of code:
我无法理解这段代码：
stringsArray.forEach(s => {
for (var name in validators) {
console.log('"' + s + '" ' +
(validators[name].isAcceptable(s) ?
' matches ' : ' doesnt match ') + name);
}
});
in particular, the s => { ...part is mysterious. It looks like s is being assigned to the next string in the array on each loop. But what is the =>part meaning? It's related to lambdas I think, but I am not following.
尤其是那s => { ...部分是神秘的。看起来 s 被分配给每个循环中数组中的下一个字符串。但是这=>部分是什么意思？它与我认为的 lambdas 有关，但我没有遵循。
回答by Josh Beam
Yeah it's a lambda (for example, similar to ECMAScript6 and Ruby, as well as some other languages.)
是的，它是一个 lambda（例如，类似于 ECMAScript6 和 Ruby，以及其他一些语言。）
Array.prototype.forEachtakes three arguments, element, index, array, so sis just the parameter name being used for element.
Array.prototype.forEach接受三个参数，element, index, array，因此s只是用于 的参数名称element。
It'd be like writing this in regular ECMAScript5:
就像用常规的 ECMAScript5 写这个一样：
stringsArray.forEach(function(s) {
for (var name in validators) {
console.log('"' + s + '" ' +
(validators[name].isAcceptable(s) ?
' matches ' : ' doesnt match ') + name);
}
});
In the above example, you didn't show the whole code, so I assume validatorsis just a plain object {}.
在上面的例子中，你没有展示整个代码，所以我假设validators只是一个普通的 object {}。
The syntax for the example you gave is actually identical to the ES6 syntax.
您给出的示例的语法实际上与 ES6 语法相同。
Check out this example from the TypeScript handbook:
从TypeScript 手册中查看此示例：
