2a09d1a4
 liuqimichale
添加宜春 天水 宣化
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'use strict';
const mimicFn = require('mimic-fn');
module.exports = (fn, opts) => {
// TODO: Remove this in v3
if (opts === true) {
throw new TypeError('The second argument is now an options object');
}
if (typeof fn !== 'function') {
throw new TypeError('Expected a function');
}
opts = opts || {};
let ret;
let called = false;
const fnName = fn.displayName || fn.name || '<anonymous>';
const onetime = function () {
if (called) {
if (opts.throw === true) {
throw new Error(`Function \`${fnName}\` can only be called once`);
}
return ret;
}
called = true;
ret = fn.apply(this, arguments);
fn = null;
return ret;
};
mimicFn(onetime, fn);
return onetime;
};
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