如何在承诺中检查/调试个别承诺的状态。
我将一堆脚本节点推入没有src
属性中的一系列承诺,这些脚本节点设置了src
,然后resolve> resolve
s或拒绝
s,分别onload
或onerror
。所有这些均以promise.ly
等待的方式调用。问题是,它永远不会停止等待。我认为一些个人承诺正在解决或拒绝,但是我不知道如何调试哪些不是。
function loadScript (script) {
return new Promise(function(resolve, reject) {
// this happens for every script
script.setAttribute("src", script.getAttribute("data-src"));
script.onload = _ => resolve(script.src);
script.onerror = _ => reject(script.src);
});
}
// loadScripts : (graph, int) -> (string array) promise
async function loadScripts(g, order = 1) {
if (!g.has(order))
return []
else
return [
...await Promise.all(g.get(order).map(loadScript)),
// the script stops here after the first pass and never executes the
// next line. It just ... awaits the previous line
...await loadScripts(g, order + 1)
]
}
我通过在Chrome Devtools和Steppping中设置断点来实现这一点,但是我不确定,一旦我们坐着等待,如何检查个人承诺的状态,看看哪些正在解决,哪些仍在。
I'm shoving a bunch of script nodes with no src
attribute into an array of promises that sets the src
and then resolve
s or reject
s, respectively onload
or onerror
. All of these are called in a Promise.all
which I await
. The problem is, it never stops waiting. I presume some of the individual promises are resolving or rejecting, but I can't figure out how to debug which ones aren't.
function loadScript (script) {
return new Promise(function(resolve, reject) {
// this happens for every script
script.setAttribute("src", script.getAttribute("data-src"));
script.onload = _ => resolve(script.src);
script.onerror = _ => reject(script.src);
});
}
// loadScripts : (graph, int) -> (string array) promise
async function loadScripts(g, order = 1) {
if (!g.has(order))
return []
else
return [
...await Promise.all(g.get(order).map(loadScript)),
// the script stops here after the first pass and never executes the
// next line. It just ... awaits the previous line
...await loadScripts(g, order + 1)
]
}
I got to this point by setting breakpoints in Chrome devtools and stepping, but I'm not sure, once we're sitting and awaiting, how to check the state of the individual promises, to see which ones are resolving and which are still pending.
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